Activation of an industrial catalyst for propylene polymerization and development of a novel method for the controllable formation of Ziegler-Natta catalyst supports [Elektronische Ressource] / Christian Hanisch

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TECHNISCHE UNIVERSITÄT MÜNCHENFakultät für ChemieWACKER-Lehrstuhl für Makromolekulare ChemieActivation of an Industrial Catalyst for PropylenePolymerization and Development of a NovelMethod for the Controllable Formation ofZiegler-Natta Catalyst SupportsChristian HanischVollständiger Abdruck der von der Fakultät für Chemie derTechnischen Universität München zur Erlangung des akademischenGrades einesDoktors der Naturwissenschaften (Dr.rer.nat.)genehmigten Dissertation.Vorsitzender: Univ.-Prof.Dr.Kai-Olaf HinrichsenPrüfer der Dissertation:1. Univ.-Prof.Dr.Dr.h.c.Bernhard Rieger2.Dr.Klaus KöhlerDie Dissertation wurde am 22.01.2010 bei der Technischen UniversitätMünchen eingereicht und durch die Fakultät für Chemie am 08.04.2010angenommen.This thesis was produced at the Institut für Anorganische Chemie II, UniversitätUlm (02/2005–01/2007) and WACKER-Lehrstuhl für Makromolekulare Chemie,Technische Universität München (02/2007–01/2009), under the supervision ofProf.Dr.Dr.h.c.Bernhard Rieger.It is a pleasure to thank the many people who made this thesis possible.I would like to express my sincere gratitude to my supervisor,Prof.Dr.Dr.h.c.BernhardRieger. Withhisenthusiasm, hisinspirationandhisgreatefforts to explain things clearly and simply, he helped to make this thesis fun forme. Throughout my thesis period, he provided encouragement, sound advice, goodteaching and lots of good ideas.I would like to thank all my colleagues in Ulm and Munich.

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MÜNCHENTÄUNIVERSITTECHNISCHEChemiefürakultätFWACKER-LehrstuhlfürMakromolekulareChemie

ActivationofanIndustrialCatalystforPropylene

PolymerizationandDevelopmentofaNovel

MethodfortheControllableFormationof

ortsSuppCatalystZiegler-Natta

hHaniscChristian

VollständigerAbdruckdervonderFakultätfürChemieder
TechnischenUniversitätMünchenzurErlangungdesakademischen
einesGrades

DoktorsderNaturwissenschaften(Dr.rer.nat.)

Dissertation.genehmigten

Vorsitzender:Univ.-Prof.Dr.Kai-OlafHinrichsen
Dissertation:derPrüfer

1.Univ.-Prof.Dr.Dr.h.c.BernhardRieger
2.Univ.-Prof.Dr.KlausKöhler

DieDissertationwurdeam22.01.2010beiderTechnischenUniversität
MüncheneingereichtunddurchdieFakultätfürChemieam08.04.2010
angenommen.

ThisthesiswasproducedattheInstitutfürAnorganischeChemieII,Universität
Ulm(02/2005–01/2007)andWACKER-LehrstuhlfürMakromolekulareChemie,
TechnischeUniversitätMünchen(02/2007–01/2009),underthesupervisionof
Prof.Dr.Dr.h.c.BernhardRieger.

Itisapleasuretothankthemanypeoplewhomadethisthesispossible.

Iwouldliketoexpressmysinceregratitudetomysupervisor,
Prof.Dr.Dr.h.c.BernhardRieger.Withhisenthusiasm,hisinspirationandhisgreat
effortstoexplainthingsclearlyandsimply,hehelpedtomakethisthesisfunfor
me.Throughoutmythesisperiod,heprovidedencouragement,soundadvice,good
teachingandlotsofgoodideas.

IwouldliketothankallmycolleaguesinUlmandMunich.MostnotablyIwould
liketothankDr.CarstenTrollforhispatienthelpwithallthemachinery,Dr.Sergei
Vaginforhishelpwithallsortsofanalytics,Dr.FlorianMögeleforbeingagreatlab
mateandFelixSchulzforthegreatdiscussionsandNMRmeasurements.Andto
allthe“Makros”:ItwasgreattospendmytimewithyouallandIwishyousuccess
inallofyourendeavours.

SpecialthanksgotoDr.LiyiChen:Yourhelp,adviceandourdiscussionswerein-
ou!yThankaluable.v

Iwouldalsoliketothankmyparentsfortheirsupportandhelpduringthecourse
ofthisthesis:Thankyou!

Lastbutnotleast,Iwouldliketothankmywife,Katrin,forherhelp,patience,
enduranceandlove:Iwouldhavebeenlostwithoutyou!

Abstract

Theaimofthisworkwastwofold:First,theactivityofapre-commercialindustrial
Ziegler-Nattacatalystwastobeenhanced(“activated”)andsecond,anovelmethod
forthecontrollableformationofZiegler-Nattacatalystsupportswastobedeveloped.

ActivationofanIndustrialCatalystforPropylenePolymerization

Twogranularandthreesphericalpre-commercialindustrialZiegler-Nattacatalysts
fromanindustrypartnerweretestedfortheirperformanceinslurrypolymerizations
ofpropylene.Allcatalystshadverygoodactivities.Thecatalystwiththebest
activity(S3)waschosentobeactivatedwithfourdifferenthydrocarbonsolvents(n-
hexane,n-heptane,tolueneandethylbenzene)andmixturesoftoluenewithtitanium
tetrachloride.S3washeatedinthevarioussolventsandsolventmixturesatdifferent
temperaturesandfordifferentamountsoftime.Theactivationprocedurehada
negativeeffectontheactivity.Themildestactivationcondition(30minintoluene
at95°C)removed9.5%ofthetitaniumfromthecatalyst,resultingina4.1%dropof
activity.Theharshestcondition(90minintolueneat111°CinaSoxhletapparatus)
removed50%ofthetitaniumfromthecatalystandresultedinadropofactivity
by71.7%.Theremovaloftitaniumspeciesledtoadecreaseofthepolydispersity
indexofthesubsequentlysynthesizedpolypropylenesamplesfrom3.6downto2.8.
Overthecourseofthepolymerizationexperiments,amoresuitablesetupfor
dosingthecatalystintothepressurizedreactor,thesolidburette,wasdeveloped,
drasticallyreducingthevariationofresultsbetweenequalexperiments.Compared
tothetraditionalsyringemethod,therelativestandarddeviationoftheactivityof
twoequalexperimentscouldbereducedfrom15.56%to0.41%.
AvideomicroscopyanalysisofS3wasconductedtoobservethepolymerization
insitu.Anindirectactivationwiththeco-catalyst,aimingatasimplifiedexperi-
mentpreparation,wasimplemented.Althoughpolymergrowthwasobservable,the
indirectactivationprovedtobeunsuitable.

DevelopmentofaNovelMethodfortheControllableFormationofZiegler-
ortsSuppCatalystNatta

Inspiredbyaprocess,knownaspolymerinducedliquidprecursor(PILP),anovel
methodforthecontrollableformationofsphericalZiegler-Nattacatalystsupports

viacompositesofliquidinorganicsandpolymers(CLIP)wasdeveloped.Common
supportsynthesisproceduresonlycontrolthemorphologydeliberatelyonamacro-
scopicscale.Theyieldedsphericalparticlesarecomposedofasinglebulkyphase,
withalowdegreeofmorphologicalcontrolonthemicroscopicscale.UsingtheCLIP
method,smallprimarysubmoietiesarecontrollablyassembledtoafinalsupport
particle,enablingmorphologicalcontrolonboththemicroscopicandmacroscopic
scale.Magnesiumchloride,thesupportmaterial,wasmeltedinthepresenceofethanol,
acommonprocesstoloweritsmeltingpointfrom713°Ctowellunder100°C,
dependingontheamountofethanolused.1-Decanolwasadded,forminganon-
stoichiometricnetworkwiththeMgCl2-ethanoladducts.The1-decanolservedasan
internalsurfactant,formingtheprimarysubmoieties.PEG-200wasadded,binding
separateadductstogether,likeacement.At130°Candundervigorousagitation,
theCLIPphaseformed.Thedropletswerethenquicklysolidifiedinn-pentaneat
ca.−45°C,yieldingaperfectlysphericalsupportprecursorwithaparticlediameter
ofxa,max=58µm.Differentshort-chainalcohols(methanol,ethanol,1-propanol),
longchainalcohols(1-octanol,1-decanol),differentbinders(PEG-200,PEG-400,
PPG-425,PDMS,PolyTHF-250),differentreactiontemperaturesanddifferentre-
actantratiosweretestedfortheirperformancetoyieldsphericalsupportprecursors.
Aprecursor,synthesizedwiththeoptimalcombinationofthereactants(ethanol,1-
decanol,PEG-200),wasdealcoholatedtoobtainthefinalsupportmaterial.Several
thermalandchemicalproceduresweretestedtoremovethealcoholfromthesupport
precursor,ofwhichthetreatmentwithtetrachlorosilaneprovedtobethemostsuit-
able.Twocatalystsweresynthesizedfromthedealcoholatedsupportprecursor,one
catalystwasmadedirectlyfromtheprecursor.Thecatalystsynthesiscompriseda
treatmentwithTiCl4andDIBP(internaldonor).Thecatalystshadverylowpoly-
merizationactivities.Remarkably,thehighestactivity(0.07kgpolymerg−1catalysth−1)
wasobtainedwiththesupportwhichhadnotbeendealcoholatedpriortothecat-
alystsynthesis.Polypropylene,generatedfromsaidcatalyst,hadaverylowPDI
(2.9)andgoodstereoregularity(96.3%mmmm-pentads).

Zusammenfassung

MitdieserArbeitwurdenzweiZieleverfolgt:ZumeinensolltedieAktivitäteines
sichimEntwicklungsstadiumbefindlichenindustriellenZiegler-NattaKatalysators
erhöhtwerden(»Aktivierung«).ZumanderensollteeineneuartigeMethodeentwi-
ckeltwerden,umZiegler-NattaKatalysatorträgermiteinemhohenMaßanMor-
phologiekontrollezusynthetisieren.

AktivierungeinesIndustriellenKatalysatorsfürdiePropylenpolymeri-
sation

ZweigranulareunddreisphärischesichimEntwicklungsstadiumbefindlicheZiegler-
NattaKatalysatoreneinesIndustriepartners,wurdenaufihreLeistungsfähigkeitbei
Slurrypolymerisationengetestet.AlleKatalysatorenwiesensehrguteAktivitäts-
werteauf.DerKatalysatormitderhöchstenAktivität(S3)wurdeausgewählt,um
ihnmitvierverschiedenenkohlenwasserstoffhaltigenLösungsmitteln(n-Hexan,n-
Heptan,ToluolundEthylbenzol)undMischungenvonToluolmitTitantetrachlorid
zuaktivieren.S3wurdeindenverschiedenenLösungsmittelnundLösungsmittel-
gemischenbeiunterschiedlichenTemperaturenundfürunterschiedlichlangeZeiten
erhitzt.DieAktivierunghatteeinennegativenEinflussaufdieAktivität.Unterden
mildestenBedingungen(30mininToluolbei95°C)wurde9,5%desTitansvomKa-
talysatorentfernt,waszueinerVerringerungderAktivitätum4,1%führte.Unter
dendrastischstenBedingungen(90mininToluolbei111°CineinerSoxhletappa-
ratur)wurde50%desTitansentfernt,woraufdieAktivitätum71,7%sank.Die
partielleEntfernungderTitanspeziesführteaußerdemzueinerVerringerungdes
PolydispersitätsindexdernachfolgendhergestelltenPolypropylenprobenvon3,6auf
.8,2WährendderDurchführungderPolymerisationsexperimentewurdeeinegeeigne-
tereMethodeentwickelt,denKatalysatorindenunterDruckstehendenReaktorzu
dosieren,wodurchdieAbweichungzwischenzweiidentischenExperimentendrastisch
reduziertwerdenkonnte.MithilfederFeststoffbürettekonnteimVergleichzurtra-
ditionellenSpritzenmethodedierelativeStandardabweichungvonzweiidentischen
Experimentenvon15,56%auf0,41%gesenktwerden.
EineVideomikroskopieanalysewurdedurchgeführt,umdiePolymerisationvon
S3insituzubeobachten.EineindirekteMethodederAktivierungmitdemCo-

Katalysatorwurdeimplementiert,umdieDurchführungdesExperimentszuver-
einfachen.ObgleicheinPolymerwachstumzubeobachtenwar,zeigtesich,dassdie
indirekteAktivierungnichtfüreineoptimaleDurchführunggeeignetwar.

EntwicklungeinerNeuartigenMethodefürdieKontrollierteSynthese
KatalysatorträgernZiegler-Nattaonv

InspiriertdurchdenPILP-Prozess(polymerinducedliquidprecursor)wurdeeine
neuartigeMethodefürdiekontrollierteSynthesesphärischerZiegler-NattaKata-
lysatorträgerdurchKompositeflüssigerAnorganikaundPolymere(compositesof
liquidinorganicsandpolymers,CLIP)entwickelt.ÜblicheTrägersynthesenhaben
nuraufmakroskopischerEbeneeinenEinflussaufdieMorphologie.AufdieseWeise
synthetisiertesphärischePartikelbestehenauseinereinzigenBulkphasemitgeringer
MorphologiekontrolleimmikroskopischenMaßstab.MitderCLIP-Methodewerden
kleineprimäreSubeinheitenkontrolliertzueinemfertigenTrägerpartikelzusammen-
gesetzt,wodurchsowohlimmikroskopischenalsauchimmakroskopischenMaßstab
eineMorphologiekontrolleermöglichtwird.
DasTrägermaterialMagnesiumchloridwurdeinGegenwartvonEthanolgeschmol-
zen–eineüblicheMethode,umdenSchmelzpunktvon713°Cbisweitunter100°C
(jenachMengeanEthanol)zubringen.NachderZugabevon1-Decanolbilde-
tesicheinnichtstöchiometrischesNetzwerkmitdenMgCl2-EthanolAddukten.1-
DecanolfungiertedabeialsinternesTensidbeiderBildungderprimärenSubein-
heiten.WeiterwurdePEG-200hinzugegeben,wodurchdieverschiedenenAddukte
zusammengefügtwurden.Bei130°CundunterstarkemRührenbildetesichdann
dieCLIP-Phase.DieTröpfchenwurdendaraufhinzügiginn-Pentanbeica.−45°C
eingebracht,wodurchsicheineperfektsphärischeTrägervorstufemiteinemParti-
keldurchmesservonxa,max=58µmbildete.VerschiedenekurzkettigeAlkohole(Me-
thanol,Ethanol,1-Propanol),langkettigeAlkohole(1-Octanol,1-Decanol),verschie-
deneBindesubstanzen(PEG-200,PEG-400,PPG-425,PDMS,PolyTHF-250),un-
terschiedlicheReaktionstemperaturenundunterschiedlicheReaktandenverhältnisse
wurdenaufihreFähigkeithinuntersucht,sphärischeTrägervorstufenzubilden.Eine
Vorstufe,synthetisiertmitderoptimalenKombinationvonReaktanden(Ethanol,1-
Decanol,PEG-200),wurdeentalkoholisiert,umfertigesTrägermaterialzuerzeugen.
UnterschiedlichethermischeundchemischeMethodenwurdenuntersucht,umdie
AlkoholevonderVorstufezuentfernen.Esstelltesichheraus,dasseineBehandlung

mitTetrachlorsilandiehierfürgeeignetsteMethodewar.ZweiKatalysatorenwurden

mitderentalkoholisiertenVorstufe,einermitderreinenVorstufesynthetisiert.In

derKatalysatorsynthesewurdendiePartikelmitTiCl4undDIBP(internerDonor)
behandelt.DieKatalysatorenzeigteneinesehrgeringePolymerisationsaktivität.

ErstaunlicherweisewarderKatalysatoramaktivsten(0,07kgPolymerg−1Katalysatorh−1),
derausdernichtentalkoholisiertenVorstufesynthetisiertwurde.Dasmitdiesem

KatalysatorerzeugtePolypropylenhatteeinensehr

gute

Stereoregularität

3,96(%

taden).en-Pmmmm

niedrigen

PDI

2()9,

und

eine

Für

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tstenCon

Nomenclature

thesisthisinincludedPublication

ductiontroIn1

iv

vi

1

5kgroundBac22.1Ziegler-NattaCatalysts..........................5
2.1.1Mechanism............................6
2.1.2MagnesiumChlorideasaSupportMaterial...........9
2.1.3ActivationwithAluminumAlkyls................13
2.1.4ReplicationandFragmentation.................14

aMotiv3ntio

19

4ActivationofanIndustrialCatalyst21
4.1Overview..................................21
4.2Catalysts.................................22
4.2.1Pre-CommercialCatalysts....................22
4.2.2CommercialCatalysts......................28
4.3PolymerizationsBeforeActivation....................28
4.3.1PolymerizationPreparation...................30
4.3.2CatalystActivity.........................31
4.3.3MolecularMass..........................32
4.3.4StatisticalConsiderations....................35
4.4Activation.................................36
4.4.1ActivationProcedure.......................37
4.5PolymerizationsAfterActivation....................38

i

5

6

4.5.1CatalystActivity.........................38
4.5.2PolymerMolecularMasses....................40
4.5.3StereoregularityDeterminationbyNMRSpectroscopy....41
4.6VideoMicroscopyPolymerization....................44
4.6.1ExperimentalPreparationandAnalysis.............44
4.6.2VideoMicroscopyPolymerizationofS3.............45

NovelMethodfortheSynthesisofCatalystSupports49
5.1Overview..................................49
5.2SupportPrecursorSynthesis.......................49
5.2.1InitialThoughts..........................49
5.2.2ExperimentationPreparation..................51
5.2.3NovelSynthesisMethod.....................52
5.3Dealcoholation..............................56
5.3.1ThermalDealcoholation.....................56
5.3.2ChemicalDealcoholation.....................57
5.4VerificationExperiments.........................59
5.4.11-Decanol.............................59
5.4.2PEG-200..............................61
5.4.3Variationofthe1-Decanol/PEG-200Ratio...........62
5.4.4VariationoftheReactionTemperature.............64
5.4.5VariationoftheAlcoholsandBinder..............64
5.5ProposedCompositeFormationMechanism..............69
5.6CatalystSynthesis............................72
5.7Polymerizations..............................75

79SectiontalerimenExp6.1GeneralRemarks.............................79
6.1.1InertGasTechnique.......................79
6.1.2Drying...............................79
6.1.3Chemicals.............................80
6.1.4PolymerizationProcedure....................80
6.1.5ParticleSizeDistribution.....................81
6.1.6StereoregularityDeterminationbyNMRSpectroscopy....81
6.2Equipment.................................81

ii

6.2.1PolymerizationAutoclave....................81
6.2.2VideoMicroscopySetup.....................82
6.2.3ScanningElectronMicroscopy,EnergyDispersiveX-RaySpec-
troscopy..............................84
6.2.4NuclearMagneticResonanceSpectrometer...........85
6.2.5HighTemperatureGelPermeationChromatograph......85
6.2.6SolidBurette...........................85
6.3ActivationofIndustrialCatalysts....................86
6.3.1StandardActivationProcedure.................86
6.3.2SynthesesofActivatedCatalysts................86
6.3.3PolymerizationintheVideoMicroscopeAutoclave......88
6.4NovelMethodfortheSynthesisofCatalystSupports.........88
6.4.1StandardSupportPrecursorSynthesisProcedure.......88
6.4.2SynthesesofSupportPrecursorsandCatalystSupports....89
6.4.3Polymerizations..........................92

yBibliograph

FiguresofList

ablesTofList

VitaeCurriculum

iii

102

105

107

109

Nomenclature

aABSECEDCLIPCPMCSMDIBPDIPSDMSOEBEDXEDFT-IRGPCHT-GPCICIIDLMMnMwMGMMMDMPINMRPDIPDMSPEPEGPFMPILPPOC

yctivitAAreaelectronk-scatteredcaBdiametertalenCircle-equivCompositesofliquidinorganicsandpolymers
Chargepercolationmechanism
delmoCore-shellthalatephyliisobutDsilanexyyldimethoDiisopropxidesulfolyDimethenzoateylbEthdonorExternalEnergy-dispersiveX-rayspectroscopy
Fouriertransforminfraredspectroscopy
Gelpermeationchromatography
High-temperaturegelpermeationchromatography
IndustriesChemicalerialImpInternaldonor
ymicroscoptLighNumberaveragemolecularmass
Weightaveragemolecularmass
delmograinMultiistributiondmassMoleculark-InstituteMax-PlancresonancemagneticNuclearPolydispersityindex
xane)siloyloly(dimethPyleneetholyPglycol)yleneoly(ethPPolymerflowmodel
precursorliquidinducedolymerPo-Phthaloylchloride

iv

PPPPGPSDD&RTRSmmmmSylmethtotalSBSEMSEVTCBTEATHFVMx50xmax,aZN

yleneolypropPglycol)yleneoly(propPdistributionsizearticlePResearchandDevelopment
eraturempteomRoAreaofthemmmm-pentadmethylpeakin13C-NMRspectroscopy.
Areaofallmethylpeaksin13C-NMRspectroscopy.
buretteolidSymicroscopelectronScanningolumevtalenSphere-equiv1,2,4-Trichlorobenzene
umylaluminriethTydrofuraneetrahTemicroscopVideoMedianvalueofparticlesizedistribution
Modevalueofparticlesizedistribution
Ziegler-Natta

Note:SIunits,commonnon-SIunits,elementalsymbolsandchemicalformulaearenot
itemized.

v

vi

–509

.516–509

2009Sci.Chem.J.B:Naturforsch.,Z.thesis

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,64b

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Rieger,

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1Chapter

ductiontroIn

«Fattoilpolipropilene»(“madethepolypropylene”)1–asmallnoteinGiulioNatta’s
labbookmarkedthebeginningofasuccessstory.Polypropyleneisatpresentthe
secondmostproducedpolymerworldwide(45.1Mt,20072),withonlythevarieties
ofpolyethylenehavingalargermarketshare(71.0Mt,20073).Natta’sdiscoveryof
stereospecificpolymerizationofα-olefins4–10iscloselyrelatedtothebreakthrough
worksofKarlZiegleronorganometallicmixedcatalystsforthepolymerizationof
olefins,the“Mülheimmixedcatalysts”forwhichNattalatercoinedtheterm“Ziegler
catalysts”.11ItwasonOctober26,1953,whenoneofZiegler’sdiplomastudents,
HeinzBreil,producedpolyethyleneatsofarunprecedentedmildconditions(approx.
100°Cand100bar)usingzirconiumacetylacetonate,leadingtothepublicationof
Ziegler’sfamouspatentin1953.12Sofar,(lowdensity)polyethylenewasonlyac-
cessibleviatechnicallydemandingroutes,suchasfreeradicalpolymerizationin
theICIprocesswithpressuresupto3000bar.13Ziegler’sinitialexperimentswere
quicklyextendedanditwassoonthereafterwhenitwasdiscovered,thatanother
latetransitionmetalcomponent–titaniumtetrachloride–incombinationwithtri-
ethylaluminumisevenmoreactiveinthepolymerizationofethylenethanzirconium,
yieldinghigh-molecular-weightpolyethylene.14Thecatalystsystemwassoonopti-
mizedtoworkatnormalpressure,15whichwasemphasizedbychoosingamodified
food-preservingjarasapolymerizationreactor(aphotographofthisreactorcanbe
foundinMülhaupt’sreviewarticlefrom200316).Besidesthescientificrelevance,
Ziegler’sfindingshadagreatimpactontheeconomicsituationoftheMax-Planck-
Institut(MPI)fürKohlenforschung,whosedirectorhewasfrom1949until1969.
AmongthefirstlicenseeswasMontecatiniinItaly,acompanycloselyaffiliatedto

1

2

GiulioNatta.AspartofanearlierlicenseagreementbetweenMontecatiniandthe
MPIinMülheim–coveringneworganoaluminumreactions–Nattahadbeenable
toplaceresearchassistantsinZiegler’slaboratory.Nattahadcloselybeenfollowing
Ziegler’swork,especiallyafterhehadattendedhislectureattheAnnualMeetingof
theGesellschaftDeutscherChemiker1952inFrankfurt.17Duetothelicenseagree-
mentbetweentheMülheiminstituteandMontecatini,Nattahadaccesstoextensive
informationonZiegler’sresearchandonMarch11,1954,Nattawasabletopoly-
merizepropyleneusingZiegler’scatalystsystem.Theheptane-insolublefractionof
theyieldedsubstancehadameltingpointabove160°C.Natta,beinganexpert
inX-rayspectroscopy,identifiedthisreactionproductashighlycrystallineisotac-
ticpolypropyleneandtheotherfractionsascrystallinesyndiotacticpolypropylene
andamorphousatacticpolypropylene.7,10,18Thegreeknamesofthestereoregular
polymersweredevisedbyNatta’swife,Rosita,wellversedinclassicallanguages.19
Actually,Natta’sfirstpublicationonthesefindings,intheJournaloftheAmerican
ChemicalSociety,submittedonDecember10,1954,wasinitiallyrejectedbecause
Nattadidn’tdisclosedetailedinformationonthecatalyst,becauseofhistiesto
Montecatini.19HiscloserelationstoMontecatiniwerealsothereason,whyNatta
didnottellZieglerabouthisfindingswhilevisitingMülheimuntilafterthefirstpub-
lication,whichwasresentedbyZieglerafterallthehelphehadgivenhim.Thefirst
patentonthesynthesisofpolypropylenewithZieglercatalystswasfiledbyZieglerin
August1954whohadalsobeeninvestigatingthepolymerizationofpropyleneearly
on.20Theindustrialproductionofhigh-densitypolyethylene(Hostalen)started1955
atFarbwerkeHoechstinFrankfurt.Theproductionofisotacticpolypropylene(Mo-
plen)started1957atMontecatini’splantinFerrara,Italy.ZieglerandNattawere
awardedtheNobelPrizeinChemistry1963“fortheirdiscoveriesinthefieldofthe
chemistryandtechnologyofhighpolymers”.21,22ArneFredga,whointroducedthe
laureatesduringtheceremony,saidaboutNatta:“Naturesynthesizesmanystereo-
regularpolymers,forexample,celluloseandrubber.Thisabilityhassofarbeen
thoughttobeamonopolyofNatureoperatingwithbiocatalystsknownasenzymes.
ButnowProfessorNattahasbrokenthismonopoly.”23

(a)

Outside

of

the

unghohlenforscK

Figure

1.1:

k-InstitutMax-Planc

Mülheinim/Ruhr.

für

k-InstitutMax-Planc

für

(b)

Karl

and

Ziegler’s

diploma,

Mülheim.

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1963

elNob

atydisplaon

in

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3

medal

MPIthe

Mülheim/Ruhr.

in

4

In1967,Montedison(ajointventureofMontecatiniandEdison)decidedtolicense
apolyethyleneprocessfromPhilipsPetroleum–ashort-sighteddecision,probably
promotedbytheEdisonpeoplewhohadnopolymerbackgroundandlittleinterest
inresearch.ThePhilipsandcompetitorprocessesappliedsocalledfirstgeneration
Ziegler-Nattacatalysts,basicallyaluminum-reducedTiCl3.However,theactivity
andstereoregularity(forthepolymerizationofpropylene)waspoor,necessitating
postprocessingsteps,suchasdeashingandextraction.Licensingapolymeriza-
tionprocesswasmuchtothedismayoftheR&DdirectorCrespi,foritwashis
companybeingcloselyinvolvedinthediscoveryofcrystallinepolypropylenebefore.
Crespi–whohadbeenoneoftheresearchers,placedbyNattainZiegler’sgroupin
Mülheim–wantedMontedisontotakethescientificleadagainandpersuadedthe
topmanagementthatthescientistsatFerraraweregiventhego-aheadtodevelop
anownPEprocesswithinoneyear,outperformingtheprocessfromPhilips.24On
theirsearchforanovelcatalystsystem,thescientistsfoundthatMgCl2–which
wasknowntobeasuitablesupportforTiCl425–leadstomuchhigheractivities,
ifitwastransformedintoitsactiveformbyballmillingbeforehand.26,27Within
theyeargiven,theFerraralaboratorywasabletodevelopaheterogeneouscatalyst,
highlyactiveforthepolymerizationofα-olefins,suchasethylene,bypassingthe
patentsfromPhilipsandSolvay,anothercompetitorforpolymerizationprocesses.
Indefianceofdecision-makerswithalackofvisions,thepersistenceofindividuals,
thehardworkandthepassionofagroupofchemiststobetheleadersintheirfield,
pavedthewaytothedevelopmentofMgCl2-basedZiegler-Nattacatalysts,widely
adoptedupuntilthepresentday.

2Chapter

kgroundBac

CatalystsZiegler-Natta2.1

Since1953and1954,theyearsZieglerandNattaconductedtheirbreakthrough
polymerizationexperiments,theZiegler-Natta(ZN)catalystshavesteadilybeen
developedfurtherbyamultitudeofscientistsaroundtheglobe.Eventhoughho-
mogeneoussingle-sitecatalystsystems,suchasmetallocenes28–32andlate-transition
metalcomplexes,33,34principallyofferanumberofadvantagesoverconventionalZN
systemsthroughliganddesign,theadvancedheterogeneous“Mülheimmixedcata-
lysts”stillproducethelargestshareoftheglobalpolyolefinmarket.Thisisdueto
suchcatalystsystemsmeetingcertainobjectives,suchasveryhighmileage,stereo-
regularity(forpropyleneandotherα-olefins),controlofpolymerproperties(mainly
molecularmassandmolecularmassdistribution)andmorphologycontroloverboth
thecatalystandpolymerparticles.Theseabilitieswereadaptedbythecatalyst
systemthroughaseriesofscientificachievements,namelythediscoveryoftheac-
tiveformofmagnesiumchloride,thestereoregulatingeffectofelectrondonorsand
theexploitationofthecatalyst-polymerreplicationphenomenon.Today,modern
MgCl2-basedZiegler-Nattacatalystsystemsevolvedtothesixth(oftenreferredto
as“next”)generation.Thegenerationdescribesthedonorsystemused(seeChap-
ter2.1.2),whichisoneofthekeystartingpointsforfuturedevelopmentsandim-
provements.ModernMgCl2-basedsystems(fourthgenerationandhigher)offerpro-
ductivitieswellover100kgpolg−cat1,extremelyhighisotacticities(mmmm=99%)and
molecularmassdistributionsintherangeof4.5until15inbulkphasepolymeriza-
35tions.

5

6

Asoutlinedinthefollowingsections,extensiveresearchisstillconductedbymany
researchgroupsthroughouttheworld,overhalfacenturyafterthegroundbreaking
discoveriesofZieglerandNattainlatetransitionmetalcatalyzedpolymerizations
andthestereoselectivepolymerizationofα-olefins.

hanismMec2.1.1

hanismMecInsertion

Themostwidelyapproved–yetnotconclusivelyconfirmed–mechanismforpoly-
merizationsbyZiegler-Nattacatalystsistheinsertionmechanism.Itisbelieved
thatthepolymerchainpropagatesbyinsertionofmonomermoleculesbetweenthe
metalandthepolymerchain.Themostimportantmechanismsproposinginsertion
aretheCossee-Arlmanmonometallicmechanism36–38andthebimetallicmechanism
proposedbySinnetal.39andNatta.40Sinnetal.andNattaproposed,thataninter-
actionincomplexesofbothtitaniumandaluminumleadstothemonomerinsertion.
AccordingtothewidelyacceptedmechanismofCosseeandArlman(Figure2.1),
anoctahedrallycoordinatedionofatransitionmetal,carryingonealkylgroupand
havingavacantposition,istheactivecenterofaZiegler-Nattacatalyst.Thealkyl
groupisintroducedthroughalkylationwithaluminumalkyls(formationofaTi−C
bond).Thepolymerizationoccursintwosteps:coordinationoftheolefinatthe
vacantcoordinationposition,withtheformationofafour-centeractivatedcomplex,
followedbycisopeningofthedoublebondandinsertionoftheolefinintotheTi−C
bond.Thechaingrowsinlengthaftereachmonomerinsertion.Cosseealsodescribes
thebackskip,anisomerizationoftheactivecenter.Aftereachmonomerinsertion
thereisaninterchangeofthepositionsofthevacancyandthegrowingchain.
Inorderforthecatalysttoyieldisotactic,syndiotacticoratacticpolymersofα-
olefins(Figure2.2),ithastoselectthecorrectenantioface(reorsi)ofthemonomer
forinsertion.Therearetwopossiblesourcesofenantiofaceselectivity:thechirality
oftheactivecenterorthegrowingchainitself.Inthecaseofpolypropylenemade
fromTiCl4-MgCl2systems,theenantiofaceselectivityisundercontroloftheactive
center(enantiomorphicsitecontrol).Ifamonomeriserroneouslyinsertedwiththe
wrongenantioface,theselectivityoftheactivecenterisnotaltered,thusonlysingle
stereoerrorsareproduced.

Figure

2.1:

propylene.

Cossee

Figure

and

2.2:

Arlman’s

Isotactic,

hanismmec

syndiotactic

of

the

and

Ziegler-Natta

atactic

p

p

nolymerizatio

lenyolyprop.e

7

of

8

hanismMecercolationPCharge

Recently,thechargepercolationmechanism(CPM)hasbeenproposedbyStoiljković
etal.41–43Accordingtothisproposition,thetitaniumspeciesandthemonomerare
thereactantsofthepolymerizationandthesupportisthecatalyst.Stoiljković
etal.elaboratethatthelatetransitionmetalonthesupportexistsindifferent
oxidationstates(e.g.+2,+3and+4forTi)aftertheactivationwithalkylaluminum
compounds(seeChapter2.1.3)andthattheycanbeeasilytransformedfromone
oxidationstatetoanother.Incontrasttotheinsertionmechanism,theCPMacts
ontheassumption,thatthemonomerisadsorbedontheentiresupportsurface,
notonlyattheactivecenterduringinsertion.The“totaladsorption”hasbeen
hintedatquiteearly,44yetithadbeenmostlyabandonedduetothewidespread
adoptionoftheinsertionmechanism.AccordingtotheCPM,themonomeraidesthe
immobilizedmetalcenterstoequilibratetheirvaryingoxidationstates.Achainof
adsorbedmonomermoleculesconnectstwoimmobilizedmetalions(oxidationstates
+2and+4)byoverlappingπ-bonds,withtheterminalmoleculesbeinginsertedinto
themetalvacancies(seeFigure2.3).

Figure2.3:SchematicsofthemonomercoordinationintheChargePercolation
hanism.Mec

Thisleadstoanexcitedstageofthemonomerbridge,astheπ-electronsaredrawn
towardsthemetalwiththehigheroxidationstate(electronacceptor).Subsequently,
aprotonisattractedbythepartialnegativechargeoftheterminalmonomer,leav-
inganelectronpaironthealkylgroup.Theresultingpositivechargeontheother

9

endofthemonomerclusterrepelsaproton,whichismovedtothemetalcenter
withtheloweroxidationstate.Thenowexposedelectronpairleadstothesi-
multaneouspolymerizationofthebridgemonomers,whereastheelectronpairon
thealkylgroupmovestotheemptyorbitalofthemetalwiththehigheroxidation
state(agosticinteraction45).Duringtheequilibrationoftheoxidationstatesofthe
metalions,theentiremonomerbridgedispolymerizedatonce.Boththemetal
centersandthemonomerbridgearechemicallyalteredduringthepolymerization.
Theformeraredeactivatedandthelatterarepolymerized,hencetheyaredefined
asreactants.Thesupportallowsboththeoxido-reductionofthemetalsandthe
polymerizationofthemonomeratthesamelocation,inthesameprocess.The
supportisnotchemicallychangedbyimmobilizingthemetalandbyadsorptionof
themonomer.Thereforeitisthecatalystforthepolymerization.Stoiljkovićetal.
reportofahighcompatibilityoftheCPMwithempiricalexperienceandexperimen-
talresultsachievedsincethediscoveryofZNpolymerization.Quitedescriptiveisa
findingofXuandCheng:Inthecaseofstyrenepolymerizationusingfourdifferent
titanocene/methylaluminoxanesystems,theywereabletoshowthatthepolymer
yieldcorrelateswithincreasingTi3+anddecreasingTi2+andTi4+concentrations.46

erminationTChainTheterminationofthegrowingchainismostlycausedbychaintransferreactions,
includingtransfertomonomer,tometalalkylsandtothetransferagent,andalso
causedbythermalcleavageoftheactivecenterinvolvingβ-hydrogenelimination.
Inmanycases,atransferagent,suchasH2,isdeliberatelyintroducedintothe
polymerizationsystemforcontrolofthemolecularweightoftheproduct.

2.1.2MagnesiumChlorideasaSupportMaterial
ThediscoveryofMgCl2beingasuitablesupportforTiCl4byShellin196225was
ofratherserendipitousnature,yetitwassoonthereafterscientificallyjustified.The
ionicradiiofMg2+andTi4+areverysimilar(Paulingionicradius:Mg2+=0.65Å
andTi4+=0.68Å).Furthermore,bothMg2+andTi3+ionscoordinateoctahedrally
andhavecomparablemetal-chlorinebondlengths(Mg−Cl=2.57ÅandTi−Cl=
2.51Å47),thusenablingtheepitacticadsorptionofTiCl4ontheMgCl2surface.The
crystallinestructureofMgCl2(αandβforms)isnotactivetowardscoordination.

10

Theplatlet-likemorphologyofMgCl2crystalsexposesthecoordinativelysaturated
basal(001)planes,whereamagnesiumatomiscoordinatedbysixchlorineatoms
andhencehasnofreecoordinationsite.48
MgCl2canbeactivatedtodevelopcrystalliteswithcoordinationsitesforother
moleculesbytransformationintotheδform.Theactivationcanbeachievedby
mechanicalandchemicalprocedures.Intheformercasetheactivationisattained
bymillingMgCl2forseveraldays.49,50Forthechemicalactivationthereexistsa
multitudeofpossibilities.Predominantarethereactionofmetallicmagnesium
withsuitablealkylchlorides51andthetreatmentofMgCl2withLewisbases.52,53
ActiveMgCl2canalsobegainedthroughrecrystallizationviaprecipitationofMgCl2-
solutionswithSiCl4.54Averyeffectivemethod,applyingtheapproachwithLewis
bases,istheformationofMgCl2-ethanoladducts.55,56Theethanolconsiderably
lowersthemeltingpointoftheMgCl2(713°C)andallows–usuallywiththeaidof
asuitablesurfactant57–theformationofsphericalcatalystsupports.58
ActivatingMgCl2willresultincrystallitesmadeupfromlateralcutsurfacescor-
respondingtothe(110)and(100)planeswithfour-coordinated(withtwochlorine
vacancies)andfive-coordinated(withonechlorinevacancy)magnesiumatoms.59In
caseofballmilling,the(110)surfaceisgeneratedmorerapidlythan(100).60
Duringcatalystsynthesis,monomericTiCl4moleculesandTiCl3fragmentspref-
erentiallycomplexalongthe(110)lateralcutsofactivatedMgCl2ratherthanon
the(100)cuts,whereasdimericTi2Cl8favorablycomplexesalongthe(100)lat-
eralcuts.61,62Busicoetal.proposedthatthedimericspecieswerehighlyisospecific
andthemonomericspecieswereaspecific.63Thispropositionwasrecentlybacked
bythe“island-model”,statingthatTispeciesclosetoeachother(asiftheywere
onanislandinaseaofMgCl2)areisospecificandmonomericspeciesareaspe-
cific.64,65Furthermore,Correaetal.statethatactivecentersonthe(110)faceare
atacticunlessflankedbytwodonors(110)-bridgecoordinated(i.e.,thetwooxygen
atomsofadonormoleculecoordinatetodifferentMgatoms).66FT-IRandRaman
spectroscopicstudiesbyBrambillaetal.showthatthecomplexescanbesepa-
ratedbytheirstability:Monomerictitaniumspeciesinatetrahedralcoordination
on(110)anddimericspeciesinanoctahedralcoordinationon(100)areunsta-
ble.Onlymonomerictitaniumspeciesinanoctahedralcoordinationon(110)are
stable.Washingwithn-hexaneremovessuchunstablecomplexesaswellasexcess
(physisorbed)TiCl4.60,67

11

Corradinietal.andBusicoetal.proposedathree-sitesmodelintermsofequilib-
riuminterconversionbetweenthreekindsofstereospecificactivesitesnamelyhighly
isospecific,poorlyisospecificandsyndiospecificsitestoexplainthestereoblockchar-
acteristicsofPPsynthesizedbyMgCl2supportedZNcatalysts.68–70Basedonthis
model,Liuetal.proposedaplausiblemechanismoftheformationandtransforma-
tionofstereospecificactivesites.71Theyreported,thatthehighestisospecificityof
activessitesisderivedfromtheintroductionofbulkyalkylgroupsintotheligand
positionsduringpretreatmentwiththeAl-alkylco-catalyst.
ThesurfaceenvironmentofZiegler-Nattacatalystsishighlycomplex.Themul-
tiplicityofdifferentactivespeciesinvolvedandthecomplexityoftheMgCl2surface
structuresimpededafullunderstandingofthemechanismsinvolveduntilthepresent
day.Afterare-evaluationofthecrystalstructureofMgCl2supports,Busicoetal.
concludedthatthesurfacewithfive-coordinateMgcationsshouldbeindexedas
(104)ratherthan(100)andthatthisisthedominantlateralterminationinacti-
vatedMgCl2.48Four-coordinateMgcationson(110)edgesandotherMgsitesof
higherunsaturationmakeuponlyasmallfraction(ca.10–20%)ofactivatedMg.48,72
Internaldonors(ID)–Lewisbasesofvitalimportanceforpolymerizationbecause
oftheirstereoregulatingeffect(seebelow)–havetheabilitytosteertheformationof
aparticularMgCl2crystallitefaceduringcatalystpreparation.73Forexample,using
amonoestersuchasethylbenzoate(EB)oradiestersuchasdiisobutylphthalate
(DIBP)asaninternaldonorleadstotheformationofboththe(110)and(104)
crystallitefacesofMgCl2,yetinthepresenceofa1,3-diether,the(110)planeis
74,75generated.tiallypreferenItiswellknown,thatinternal(orexternal)donors,addedtoMgCl2-supported
Ziegler-Nattacatalysts,stereoregulatetheactivecenters,thusimprovingtheiso-
tacticityofpolypropylene.47,53,76,77Intheabsenceofsuchdonors,only40–50%of
thepolymerisisotactic.67Thedonorsystemsusedhaveevolvedovertime,which
isalsoreflectedinthecatalyst“generation”:Thefirstfamilyofinternal/external
donorsconsistedofethylbenzoate(ID)andaromaticesterssuchasmethylp-toluate
(ED).78,79Theywerereplacedwiththecouplediisobutylphthalate(ID)/alkylalkoxy-
silane(ED)24,80,81and,morerecently,withdiethers,suchas2,2-disubstituted-1,3-di-
methoxypropane.82,83Theaboveelectrondonors/donorcouplesdefine,respectively,
thethird,fourth,andfifthgenerationofZiegler-Nattacatalystsystems.Quitere-
cently,a“next”generationofMgCl2-TiCl4systemswasdeveloped,whichisbased

12

onsuccinatesasinternaldonors.Itisabletoprovidebothcontrolledpolymer
stereoregularity(eitherveryhighorlow)andbroadMMD.84Likephthalatedonors
theyarequiteflexibleintheircoordinationbehaviorbecauseoftheirfour-atom
spacerbetweencoordinatingoxygenatoms.Thisresultsinabroadervarietyof
activesitesandleadstolargerPDIvaluesoftheproducedpolymer.66Indiethers
andalkoxysilanestheshortspacerimposes(110)-chelatecoordination,resultingin
alargerhomogeneityofactivesites.66Chadwicketal.presentedacorrelationbe-
tweenthePDIandthediisobutylphthalateanddietherdonorsystem:85Theactive
speciesinthedietherdonorsystemarequiteuniform,significant2,1-insertiontakes
placeatbothhighlyisospecificandweaklyisospecificactivespecies.Theactive
speciesinphthalatesystemsundergoless2,1-insertionandarethereforelessrespon-
sivetochaintransferwithhydrogen.Thiswillthereforeleadtotheformationofa
highmolecularweightfraction,broadeningthemolecularmassdistribution(MMD).
Ribouretal.report,thatadecreasingtitaniumandactivesitecontentofthecat-
alystleadstoanarrowingoftheMMD.86,87Teranoetal.furthermorereport,that
aloweringofthetitaniumconcentrationincatalystsystemswithanID,increases
88.ystereoregularittheAnanecdote,underliningthatpurelucksometimesleadstogreatfindings,isthe
discoveryofalkylalkoxysilanesasED.Analkoxysilane/TEAmixture,resultingin
poorpolymerizationperformance,wasleftontheshelfforseveralweeksandwas
thentriedagain.Ithadreactedtothealkyl-speciesandhadaverypositiveeffect
onthestereoregularityofthepolymerization.24
AccordingtotheproposedmechanismforthestereoregulationofIDs,theycre-
atethebulkinessforthemonomertobeorientedattheactivecenterinacertain
way.69,89IsolatedTisitesmaybeaspecificorhavelowisospecificitybecausesteric
hindrancearoundthemmaybeinsufficient.90Accordingly,Wadaetal.suggestthat
thedonorsworkbestonsuchaspecificisolatedmonomericTispecies.88Thedonors
cancoordinatearoundthetitaniumsitesandmakethemhighlystereospecific.
Theco-adsorptionoftheIDandTiCl4isnoncompetitivebecausetheTiCl4
complexesaremuchweakerthanthoseoftheIDonthesurface.72TheIDcovering
isamatrixforTiCl4.AftertheIDhasoccupiedalltheaccessibleMgcations,the
TiCl4occupiestherestID-freeadsorptionsites.72Recently,Leeetal.reporteda
differentmechanismforthe1,3-diether:SuchanIDdoesn’ttransformaspecificsites
onthe(110)facetoisospecificsites.Itratherprevents–byselectiveadsorption

13

on(110)–theformationofaspecificactivesiteswhichelevatestheconcentration
ofisospecificsitesonthe(100)planes,thusresultinginahigherisotacticityand
91y.ductivitproTheID,coordinatedtoMgCl2,mustnotbedisplacedtoensurehighstereo-
specificity.Yet,upuntil80%ofIDslikeethylbenzoateanddiisobutylphthalate
isremovedfromthesupportbyalkylationandcomplexationreactionswiththe
aluminum-alkylco-catalyst24(seeChapter2.1.3),necessitatingtheuseofanex-
ternaldonorinthepolymerizationtopreventthis.53Asoutlinedabove,external
donorsarearomaticestersanddiestersinthirdandfourthgenerationZNcatalysts,
respectively.Incontrast,dietherssuchas2,2-disubstituted-1,3-dimethoxypropanes
remainstronglycoordinatedtothesupportwhenthecatalystisbroughtintocon-
tactwiththeco-catalyst,sothathighstereospecificitycanbeattainedeveninthe
absenceofanexternaldonor.77

2.1.3ActivationwithAluminumAlkyls
Foranolefininsertionintoacatalyticsite,thesitemustfirstbeactivatedbya
co-catalyst,leadingtotheformationofaTi-alkylbondbyreplacementofonechlo-
rineatomcoordinatedtothetitaniumwithanalkylchain.Theco-catalyst,AlEt3,
iscombined–ifnecessary(seeabove)–withtheexternaldonor.Thefourthgen-
erationcatalystsportrayedinthiswork,containaninternaldonorcompoundas
componentofthesolidcatalystsandanexternaldonorcompoundascomponentof
theco-catalystmixture.Onthesurface,complexesoftheDIBPwithMgCl2and
TiCl4areformed,aswellascomplexesofMgCl2ando-phthaloylchloride(POC),92
whichisformedinareactionbetweenDIBPandTiCl4.Approximately80%ofthe
adsorbedcarbonylspeciesreactwithAlEt3duringcontactwiththeco-catalystmix-
ture,leadingtotheformationofvariousdialkylaluminumalkoxidesandacomplete
removalofthePOCfromthesurface.24,93,94ThecomplexesofthesilanewithAlEt3
arestronglyadsorbedonthesurfaceofthesolidcatalystandonthesurfaceofthe
productsofitsreactionswithexcessAlEt3.94
TheadditionofAlEt3ultimatelyleadstoTi−Cbondandvacantorbitalforma-
tiononthetitanium,whichisreducedfromTi+4toTi+3.95Thisactivationprocess
isaprerequisiteforeithermonomerinsertionorterminalmonomercoordination,
dependingontheappliedmechanism.

14

Figure2.4:Ti−CbondandvacantorbitalformationduringactivationwithAlEt3.

2.1.4ReplicationandFragmentation

AprominentdetailofsupportedZNcatalystsistheirabilitytoreplicatetheirshape
duringpolymerization.96,97Forexample,asphericalcatalystparticlewillyielda
sphericalpolymerparticleafterfragmentationandpolymerization.Suchbehavioris
exhibitedforexamplebycatalystN26(Figure2.5a)andthecorrespondingpolymer
N29(Figure2.5b).ThesynthesisofN26willbeexplainedinChapter5.Three
models,explainingthereplicationphenomenonofMgCl2-basedZNcatalysts,are
used.oftenmost

Core-ShelldelMo

Accordingtothecore-shellmodel(CSM),thecatalystparticledoesnotbreakup
duringpolymerization.Agrowingshellofpolymerisformedontheoutersurfaceof
thecatalyst(thecore).98–102Themonomerhastodiffusethroughthepolymershell
togainaccesstotheactivesites.Obviously,thefinalpolymerparticlewillhavethe
sameshapeasthecatalyst.Accordingtosome,catalystswithlowporosityexhibit
thisgrowthmodelduringslurrypolymerizations.103,104

(a)

SEM

imageofasphericalcatalyst(N26).

Exemplification2.5:Figure

2.6:Figure

wthgroolymerP

of

(b)SEM

image

of

a

olymerp

),N29(

withsphericalcatalystN26.

thephenomenon.replication

gcordinac

to

the

core-shell

del.mo

15

made

16

delMoMultigrain

Veryoftenapplied,themultigrainmodel(MGM)explainsthepolymerizationes-
peciallyinporoussupports.AccordingtotheMGM,themonomerquicklyreaches
alargenumberofactivesitesonthesurfaceandinsidethecatalyst,resultingina
simultaneouspolymerizationthroughouttheentirecatalyst.Thisleadstoanim-
mediatefragmentationofthecatalystparticle.99,103–105Thepolymerizationonthe
microparticlesfollowsthecore-shellmodelleadingtoamacroparticlereplicatingthe
catalyst.theofeshap

Figure2.7:Polymergrowthaccordingtothemultigrainmodel.

PolymerFlowModel

Inthepolymerflowmodel(PFM),98,106,107thecatalystfragmentsatthebeginningof
thepolymerization.Thecatalystandthepolymerbuildonephaseandthepolymer-
izationoccursatembeddedactivesites,movingradiallyoutwardswiththeforming
olymer.pTheMGMandthePFMarethemostwidelyadaptedmodelsexplainingthe
108phenomenon.replication

Figure

2.8:

olymerP

wthgro

according

to

the

p

erolym

wflo

mo

del.

17

18

3Chapter

ationMotiv

ActivationofanIndustrialCatalystforPropylenePolymer-
ization

Thefirstaimofthisworkwasthescreeningofhighlyactiveindustrialcatalystsfor
propylenepolymerization.Afterwardsamethodofactivatingoneofsaidcatalysts
(i.e.,enhancingtheactivity)wastobeappliedandtheresultingactivatedcatalyst
samplesweretobetestedforpolymerizationperformance.
Pre-commercialfourthgenerationZiegler-Nattacatalystsweresuppliedbyanindus-
trypartner.Thescreeningwastobecarriedoutbymeansofslurrypolymerizations
inlaboratoryautoclavesystems.Avideomicroscopeautoclavewasalsotobeused
forpolymerizationstogainvisualinsightintothegrowthofthepolymeronthe
ort.suppTheactivationwassupposedtobeanadditionalstepaftertheactualcatalystsyn-
thesis.Insteadofenhancingthesynthesisofthesupportandtheimpregnationwith
catalyticallyactivespecies,asimplewashingstepwastobeintroducedtothesup-
pliedready-to-usecatalysts.Theyweretobetreated(“activated”)withdifferent
hydrocarbonsolventsandmixturesthereofwithtitaniumtetrachlorideatelevated
temperaturesandlatertestedinslurrypolymerizations.

DevelopmentofaNovelMethodfortheControllableForma-
tionofZiegler-NattaCatalystSupports

Thesecondaimofthisworkwasthedevelopmentofanovelmethodforthecon-
trollableformationofsphericalZiegler-Nattacatalystsupports.Asopposedtowell-

19

20

wnkno

trolled

synthesis

cedures,rop

I

tedanw

to

thesisynez

spherical

stepwiseassemblyofmicroscaledsubmoieties,thus

yorositphigh

catalysts.

and

large

surface

area

able

to

act

as

a

dogo

particles

yielding

ortsupp

yb

a

stancesuba

for

con-

with

Ziegler-Natta

4Chapter

ActivationofanIndustrialCatalyst

4.1erviewOv

Aseriesofpre-commercialindustrialfourthgenerationZiegler-Nattacatalystswere
testedfortheirpropylenepolymerizationperformancepriortotheintendedcatalyst
activationproject.Ithelpeddevelopinganownstandardprocedureforpolymer-
izationexperimentswithheterogeneouscatalysts.Basedonastatisticalanalysisof
thesepreliminaryresults,animprovedmethodforcatalystinjectionwasdeveloped.
SphericalcatalystS3waschosenforthesubsequentactivationexperiments.It
wastestedifthecatalystactivitycouldbeincreasedbyatreatmentwithdifferent
hydrocarbonsolventsormixturesoftoluenewithTiCl4.Themodificationofthe
catalystcouldnotbedirectlyobserved,becauseoftheverylowconcentrationof
activesitesonthesupport.Themodificationisindirectlyevidencedbythepoly-
merizationperformanceofthecatalystsandbytheanalysisofpolymerproperties.
Themethodsappliedhadanegativeeffectonthecatalystactivity.However,theac-
tivationprojectdeliveredsupplementalinsightintothephenomenaaccompanying
polymerizationswithindustrialheterogeneousZiegler-Nattacatalysts.Accompa-
nyingthedecreaseoftitaniumconcentrationduetotheappliedprocedure,wasa
narrowingofthemolecularmassdistributionatconstantlevelsofhighstereoreg-
ularity.Furthermore,thedevelopmentoftheimprovedcatalystinjectionmethod
provedtobeavitalelementforbetterpolymerizationcontrolinfutureexperiments.

21

22

Catalysts4.2

CatalystsPre-Commercial4.2.1Theindustrypartnersuppliedaselectionofpre-commercialfourthgenerationZiegler-
Nattacatalysts(G1,G2andS1,S2,S3),optimizedforthepolymerizationof
ylene.prop

CatalystsularGranG1andG2aregranulartypecatalysts,optimizedforgas-phasepolymerizations.
Figure4.1aandFigure4.1bshowlightmicroscopy(LM)andscanningelectron
microscopy(SEM)imagesofG1.Asopposedtosphericalcatalysts,theyexhibita
characteristicirregularshape.Aparticlesizedistribution(PSD)analysisofG1is
showninFigure4.3a.Itrevealsabimodaldistributionwithmodevaluesxa,max1=
4µmandxa,max2=20µmandamedianx50=14µm.Themodexa,maxrepresents
themostpopulatedclassinahistogram.Multimodaldistributionshaveseveral
modevalues.Themedianx50separatesthehigherhalfofapopulationfromthe
half.erwlo

(a)LMimageofG1.(b)SEMimageofG1.
Figure4.1:GranularcatalystG1.

AscanberecognizedfromtheLMandSEMimages(Figure4.2aand4.2b)the
shapeofG2isverysimilartothatofG1.Itsparticlesize,showninFigure4.3b,is
alsobimodallydistributed(xa,max1=8µm,xa,max2=16µmandx50=17µm)but
thedifferentclassesaremoreevenlypopulated.

(a)

(a)

imageLM

G1PSD.

of

.G2

4.2:Figure

4.3:Figure

ofimageSEM(b)

GranularcatalystG2.

PSD.G2(b)

PSDsofG1andG2.

G2.

23

24

CatalystsSphericalS1,S2andS3aresphericaltypecatalysts.S1isanearlydevelopment.Figure4.4a
showsacceptablesphericallyshapedparticleswithaminoramountofsmallfrag-
ments.However,energydispersiveX-rayspectroscopy(EDX)analysisandPSD
revealproblematicissues.Figure4.4bshowsanSEM-EDXmappingimage.The
SEMimagecapturedbytheback-scatteredelectron(BSE)detectorislocatedin
theupperright-handcorner(grey).TheEDXdataforthreedifferentelementsof
choice(red:titanium;green:nickel;blue:magnesium)wasaddedtotheSEMim-
age.Strongercolorsimplyahigherdensityoftherespectiveelementonthesurface.
Thesignalsofmagnesiumandtitaniumarethestrongestbecausethecatalystcon-
sistsmainlyofmagnesiumchloride(support)andtitaniumchloride(activespecies).
Thefewnickelsignalscanbeattributedtobackgroundnoise.Foradetailedin-
troductiontothedesignandsynthesisofZiegler-Nattacatalysts,pleasereferto
Chapter2.1.Oncloserinspection,thetitaniumsignalsareunevenlydistributed
onthesurface.Suchhotspotsareundesirable.Theintricatecatalyticsystemis
inhibitedbyanexcessamountoftitaniumchlorideonthesurface.Asexplainedin
Chapter2.1.1,effectiveZiegler-Nattacatalysisonlytakesplaceiftheproperamount
ofactivespeciesisattachedtotheproperlatticeoftheMgCl2surface.

(a)LMimageofS1.

(b)SEM-EDXmappingimageofS1.

Figure4.4:SphericalcatalystS1.

AcloserlookatthecatalystbySEMrevealsmoredetails.Largecrackson
thecatalystsurfacecanbeseenonFigure4.5aand4.5b.Duringpolymerizations,
thecatalystissupposedtobreakupdeliberately.Thefragmentationduringtheso

25

calledreplicationprocess(seeChapter2.1.4)iscontrolledbythecatalyst’sstructural
enduranceandthehydraulicforceofthegrowingpolymerchain.Aporoussupport
structureisnecessaryformonomermobilitybutlargecracksasobservedinS1will
leadtocatalystdamageduringpolymerizationandeventuallytotheformationof
fines.olymerpundesired

.S1(a)

closeup.S1(b)Figure4.5:SEMimagesofsphericalcatalystS1.

APSDisshowninFigure4.6.Itismonomodal(xa,max=8µmandx50=13µm)
butnotnarrow.Thereisalongtailwithwellpopulatedclasseslargerthanxa,max.

Figure4.6:PSDofS1.

S2exhibitspropertiessimilartoS1.Alargeamountofparticlesarespherical
butthecatalyst’ssurfaceispermeatedbylargecracks(Figure4.7aand4.7b).

26

.S2(a)

closeup.S2(b)

Figure4.7:SEMimagesofsphericalcatalystS2.

ThePSDofS2(Figure4.8a)hasimprovedcomparedtoS1(xa,max=4µmand
x50=4µm).Itcanbeconsideredfairlynarrow.Thereisnoconsiderablelarge
tailofhighlypopulatedclassesabovethemodevalue.ThemodeofS2issmaller
thanthemodeofS1.AnEDXanalysisofS2ispresentedinFigure4.8b.Again,
titanium(green)isunevenlydistributedonthesupportandhotspotsarevisible.

.S2ofPSD(a)

(b)SEM-EDXmappingofS2.

Figure4.8:SphericalcatalystS2.

S3ismoreadvancedthanbothS1andS2.AstheLMimage(Figure4.9a)
indicates,theparticlesaremostlyspheres,yettherearestillsmallfragmentsvisible.
Thesurfacestructureofthecatalysthasgreatlyimproved.Therearenolarge

27

cracksvisible.Thedistributionofactivespeciesonthesurfacehasimprovedaswell
(Figure4.10b).Titanium(green)isnowevenlydistributedoverthesurfacewith
nohotspotsvisible.ThePSDofS3isshowninFigure4.10a.Theparticleshavea
slightlylargersizethanS1andS2(xa,max=12µmandx50=13µm).

(a)LMimageofS3.

(b)SEMcloseupofS3.
Figure4.9:SphericalcatalystS3.

(a)PSDofS3.(b)SEM-EDXmappingofS3.
Figure4.10:SphericalcatalystS3.
Allcatalystshaddecentactivitiesinslurrypolymerizations.Asummary,includ-
ingastatisticalinspection,ofthecatalysts’activitiesinpolymerizationexperiments
canbefoundinTable4.5(Page36).S3,beingthemostadvancedofthesupplied
sphericalcatalystsatthattime,waschosenforthesubsequentactivationstudy.No

28

granularcatalystswereselectedforactivation.Themainfocusoftheactivation
projectandthedevelopmentofanovelmethodforthecontrollableformationof
catalystsupports(seeChapter5)wasonsphericalparticles.

ParticleSizeDistributions
Table4.1presentsanoverviewofthePSDdataofthesuppliedcatalysts.

Table4.1:ParticleSizeDistributions

catalystdistributionmodexa,maxmedianx50
[µm][µm]
G1bimodal4;2014
G2bimodal8;1617
138dalmonomoS144dalmonomoS21312dalmonomoS3

dalbimoG1dalbimoG2dalmonomoS1dalmonomoS2dalmonomoS3

CatalystsCommercial4.2.2Atalaterstage,theindustrypartnerwasabletoprovidemewithtwocommercial
catalysts(G3,S4).However,sincetheactivationprojecthadadvancedfaralready
withS3,theyhavenotbeenconsideredforanyactivationexperiments.SEMimages
ofG3andS4arepresentedonlyforreferenceinFigure4.11and4.12.

4.3PolymerizationsBeforeActivation

Allcatalystsweretestedfortheirpropylenepolymerizationperformancepriorto
theprojectedactivation.Standardpolymerizationconditionswereimplementedin
closecontactwiththeindustrypartner.Theexecutionofnumerouspolymeriza-
tionsunderstandardconditionspriortotheactivationexperimentsensuredahigh
degreeofsteadyanduniformresults.Thesepreliminaryexperimentsalsoledtothe
developmentofanenhancedmethodofcatalystdosing(seeChapter4.3.4).

(a)SEMimageofG3.

(b)SEMcloseupimageofG3.

Figure4.11:CommercialgranularcatalystG3.

29

Screeningpolymerizationswereallcarriedoutina1Ldouble-mantlestirred
steelautoclave.Thepolymerizationconditionswereaimedtobekeptconstant,as
outlinedinTable4.2.Thedetailedprocedureofthepolymerizationexperimentsis
6.1.4Chapterinoutlined

Table4.2:StandardSlurryPolymerizationConditions

TemperatureT70°C
ReactorvolumeVreactor1L
Propylenepressureppropylene5.00bar
HydrogenpartialpressurepH20.36bar
SolventvolumeVsolvent350mL
Catalystamountmcatalyst15mg
PolymerizationdurationΔtpolymerization2h
Al:Si:Tiratio100:10:1

Note:Applyingtheidealgaslaw,amolarratioof6.8%hydrogeninthereactorcan
becalculated.

Toensuresignificantdataforthecatalystactivity,itisimportanttocomplywith
thepolymerizationtimethathasbeenagreedupon.Theactivityisanaveragevalue,
calculatedfromthepolymermassafterthepolymerizationtime.Atthebeginning
ofapolymerization,alargequantityofpropyleneisconsumed.Thecatalystfrag-

30

(a)SEMimageofS4.

(b)SEMcloseupimageofS4.

Figure4.12:CommercialsphericalcatalystS4.

mentsduetothegrowingpolymerchainsandfreshactivesitesbecomeaccessible
(seeChapter2.1.4foradetailedexplanationofthefragmentationandreplication
phenomena).Overthecourseofthepolymerizationthepropyleneconsumptionde-
creases.Thisisattributedtothefactthatagrowinglayerofpolymerislimiting
accesstotheactivecentersofthecatalyst.Ittakesanincreasinglylongertimefor
themonomertodiffusethroughthecatalystandthislayer.Asaresultlesspolymer
isgeneratedandtheactivitydecreases.Thus,shorterpolymerizationtimesofthe
samecatalystwouldleadtohighervaluesfortheactivity.
Thepolymerizationisanisothermalreactioninaasemibatchreactor.109Inorder
toexaminethehydrogenresponse,preliminaryexperimentswerealsocarriedoutin
theabsenceofhydrogen.Itwasexpectedthatthehydrogenactsasachainlength
limitingagent,thusloweringthemolecularweightandbroadeningtheMMDofthe
polymer.Moreover,itwasexpectedthattheadditionofhydrogenimprovesthe
activityofthecatalyst.110Thedosingprocedureforthehydrogenisexplainedin
6.1.4.Chapter

PreparationolymerizationP4.3.1Thecatalysthastobeactivated,priortothepolymerization.AsoutlinedinChap-
ter2.1.3,thesampleiscontactedwithamixtureofTEA(co-catalyst)andDIPS
(ED)andthenbroughtintothereactor,whichhasalreadybeenpressurizedwith
propylene.Adetailed,step-by-step,illustrationisgiveninChapter6.1.4.

31

4.3.2CatalystActivity
Allcatalystsexhibitedactivitiesinamutualrange,yetdifferencesbetweeneach
weresignificant.Thechosenpolymerizationconditionsmettherequirementsofthe
catalysts.Itwasunproblematictoremovetheheatoftheexothermicpolymeriza-
tionfromthesystemwithacryostat.Theamountofpolymerproducedineach
experimentwaslowenoughnottocauseheattransferproblemsduetooverfilling
ofthereactorspace.Asummaryofthepreliminarypolymerizationspriortothe
activationprojectisfoundinTable4.3.
Table4.3:SummaryoftheCatalystActivitiesBeforeActivation

kgcatalysthydrogenactivitya
olymerph∙gcatalystG1yes1.15
G2yes1.40
S1yes2.08
S2yes1.05
S3yes1.80
09.1noG160.1noG256.1noS199.0noS2S392.1no

esyG1esyG2esyS1esyS2esyS3noG1noG2noS1noS2noS3

G2ismoreactivethanG1.S1seemstobethesphericalcatalystwiththehighest
activity.Aninvestigationofthecatalystdosingtechnique,whichisdiscussedin
Chapter4.3.4,revealedthatS3hasahigheractivitythanS1.
AcomparisonoftheactivitieswithandwithouthydrogenisshowninFigure4.13.
Itcanbeseenthathydrogenhasnodefiniteeffectonthecatalysts’activities.Hy-
drogenhasapositiveeffectontheactivityofG1(5.5%higher),S1(33.3%higher)
andS2(6.1%higher).TheactivityisloweredinthepresenceofhydrogenforG2
(12.5%less)andS3(6.3%less).ThisisconsistentwiththefindingsofKouzaiet
al.whoreportthathydrogenhasnoeffectontheactivityofisospecificandaspecific

32

90sites.eactiv

Figure4.13:Comparisonofactivitieswithandwithoutthepresenceofhydrogen.

AcomparisonoftheSEM-EDXmappingimagesoftitanium(Figures4.4b,4.8b
and4.10b)andtheactivities(incl.statisticalconsiderations,Table4.5inChap-
ter4.3.4)ofS1,S2andS3(pleasetakethesolidburetteexperimentsintoac-
count)suggests,thattitaniumhotspotsimpairtheactivity.Catalystswithtitanium
hotspots(S1andS2)havealoweractivitythancatalystswithout(S3).

MassMolecular4.3.3Adeterminationofthechainlengthdistributionisanimportantaspectofpolymer
characterization.Polypropyleneisalinearhomopolymer,thusthemolecularmass
Miofeachpolymerchainisameasureforitslength.Themolecularmassesofthe
polymersweredeterminedwithhigh-temperaturegelpermeationchromatography
(HT-GPC).111InastatisticalanalysisoftheHT-GPCdata,thenumberaverage
molecularmassMnandweightaveragemolecularmassMwcanbecalculated.Mn
representsanarithmeticmeanofthemolecularmassesofallpolymerchains.With
NibeingthenumberofchainswiththemolecularmassMi,thenumberaverage
ismassmolarkMn=i=1kNi∙Mi(4.1)
Ni=1iTheweightaveragemolecularmassMwtakestheweightfractionwiofpolymerswith
themolecularmassMiintoaccount.Theweightofeachfractioniiscalculatedwith

Thustheweightfractionis

weight=Ni∙Mi

33

(4.2)

M∙Niiwi=ki=1Ni∙Mi(4.3)
TheweightaveragemolecularmassMwisthencalculatedwith
kMw=wi∙Mi(4.4)
=1iTheratiobetweentheweightaveragemolecularmassandthenumberaveragemolec-
ularmassiscalledpolydispersityindexPDIandisameasureofthedistributionof
molecularmassinasample:M
w(4.5)=PDIMnAhypotheticalpolymerconsistingonlyofchainswiththesamelengthhasapoly-
dispersityindexofMw/Mn=1.Homogeneoussingle-sitecatalystshaveaPDI≈
2.112Similarvaluescanbeachievedwithnovel,silica-supportedNi(II)catalysts.113
Ziegler-Nattacatalyststypicallyhaveamolecularmassdistributionfrom5to15.114
AsummaryofMn,MwandPDIoftheexaminedcatalystsisdisplayedinTable4.4.
Thehydrogenresponseisvisibleforbothgranularandsphericalcatalysts.Polymer-
izationsintheabsenceofhydrogengeneratepolymerswithweightaveragemolecular
massesbetween600000gmol−1and800000gmol−1.Theintroductionofhydrogen
tothereactor(6.8%,seeTable4.2)lowersthemolecularmassesconsiderablyto
valuesintherangeof250000gmol−1.ThisisalsovisualizedinFigure4.14a.The
polydispersityindexisnotconsistentlyinfluencedbytheintroductionofhydrogen.
AsvisibleinFigure4.14b,hydrogenlowersthePDIofG2,S1andS2,butelevates
thevalueforG1.
AcomparisonoftheSEM-EDXmappingimagesoftitanium(Figures4.4b,4.8b
and4.10b)reveals,thatS1andS2exhibitahigherTiconcentrationonthesurface
thanS3.ThePDIofthegeneratedpolymers(seeTable4.4)decreaseswithless
titaniumonthesurface.S1andS2haveaPDIof4.4and5.0,respectively.S3has
aPDIof3.6.AshasbeenpointedoutinChapter2.1.2,thePDIcorrelateswiththe
degreeofheterogeneityofactivesitesonthesurface.Aloweramountoftitanium
yieldscatalystswithahigherhomogeneityofactivesites,thusproducingpolymers
PDIs.erwlowith

34

Table4.4:SummaryoftheMolecularMassAveragesandPDIsbeforeActivation

catalysthydrogengMngMwPDI
molmolG1yes500002500005.0
G2yes700002300003.3
S1yes500002200004.4
S2yes500002500005.0
S3yes700002500003.6
G1no1400006000004.3
G2no1500007000004.7
S1no1200006500005.4
S2no1500008000005.3

G1G2S1S2S3G1G2S1S2

esyyesesyesyesynononono

0.53.34.40.56.33.47.44.53.5

(a)Side-by-sidecomparisonoftheweight-(b)Side-by-sidecomparisonofthepolydisper-
averagemolecularmassafterpolymeriza-sityindicesafterpolymerizationwithand
tionwithandwithouthydrogen.withouthydrogen.

Figure4.14:Weightaveragemolecularmassandpolydispersityindexagainsthy-
presence.drogen

35

ConsiderationsticalStatis4.3.4Anongoingfluctuationofcatalystactivityinidenticalexperimentscouldnotbe
explainedatfirst.Itwasrevealedthatthethenappliedsyringe-dosingtechnique
wasthecauseofthis.
Dosingexactly15mgofcatalystintothepressurizedreactorunderinertcondi-
tionswaschallengingifnotimpossibleapplyingthetraditionalsyringe-method.For
thismethod,aportionofthecatalyst–largerthanneededforasingleexperiment–
wassuspendedinahydrocarbonsolvent(e.g.,n-heptane)andstoredinaSchlenk
tube.Priortoinjectingthecatalystduringapolymerizationexperiment,theslurry
wasagitatedandanappropriateamountwasextractedwithasyringe.Theportion
wasthentransferredintoasmallpressurecylinderandinjectedintothereactor.
Twoproblemsariseusingthismethod:

1.Thecatalystconcentrationofthesampleinsidethesyringecandifferfromthe
overallslurryconcentrationbecausethesolidsettlesinsidetheSchlenktube.
Itisuncertainwhetherthesampledvolumecontainsthedesiredamountof
catalyst.Usingaliquidwithahigherviscosity(e.g.,paraffin)isofnoavail.
Itbecomesdifficulttosuspendandproperlydistributethecatalystinsuch
media.Gasbubblesformoftenduringagitationandstayintheslurry.The
trueamountofcatalystinasampletakenwithasyringefromaslurrycannot
bedeterminedwithahighdegreeofcertainty.

2.Duringeachinstanceofcatalystsampling,asignificantamountofcatalyst
adherestotheouterwallofthesyringe’scannula.Thereismorecatalysttaken
outoftheSchlenktubethanintended.Asaconsequencethenextexperiment
willbeconductedwithanunderdoseofcatalyst,sincetheoperatoranticipates
aslurrywithahighercatalystconcentration,

Forthereasonsoutlinedabove,theresultsofthepolymerizationexperimentsfluctu-
ated,visibleinalargestandarddeviationoftheactivity.Fluctuationsofactivityin
allegedlyequalexperimentswereunacceptable.Asaconsequence,thesolidburette,
amoresuitablesetupfordosingsensitivesolidcatalysts,wasdevelopedandde-
ployed.Itsdevelopmentandadvantagesoverthetraditionalmethodareexplained
indetailinChapter6.2.6.Theresultsofthescreeningofallunmodifiedcatalysts
suppliedaresummarizedinTable4.5.Thestandarddeviationoftheactivityais

36

indicated.Additionally,therelativestandarddeviationispresentedforclarification
asitvisualizesthefluctuationoftheresults.Itiscalculatedasfollows:
relativestandarddeviation=standarddeviation∙100(4.6)
meanarithmetic

Table4.5:ComparisonofDosingTechniquesontheBasisofActivityBeforeActi-
ationv

catalystdosingmethodactivityastandardrelative
deviationstandarddeviationkgolymerph∙gcatalystG1syringe1.150.5043.48%
G2syringe1.400.2820.00%
S1syringe2.080.3416.35%
S2syringe1.050.2120.00%
S3syringe1.800.2815.56%
S1solidburette1.830.063.28%
S3solidburette2.440.010.41%

syringeG1syringeG2syringeS1S2syringesyringeS3burettesolidS1burettesolidS3

%48.43%00.20%35.16%00.20%56.15%28.3%41.0

Thefluctuationoftheresultswasdramaticallydecreasedwhenthecatalysts
wereinjectedintothereactorwiththesolidburette.Therelativestandarddevia-
tionofthesingleexperimentscouldbeloweredconsiderably,givingthevaluesfor
theactivitysignificantlymorecredibility.Thesolidburettewaslaterusedforall
polymerizationswithallcatalysts.AcomparisonbetweenS1andS3–theformer
contestantsforhighestactivity–revealedthatinfactS3hasthehighestactivity.

ationctivA4.4Duringcatalystsynthesis,stableandunstabletitaniumcomplexesformonthesur-
face.Theremightevenbeexcesstitanium–stillphysisorbed–present(visibleas
Ti-hotspotsonSEM-EDXmappingimagesatsufficientconcentrations).Aslightde-
titanation(e.g.,washingwithn-hexane)isasuitablemethodtoremovethespecies
thatarenottightlyattachedtothesurfaceandtolowertheoveralltitaniumcon-
centration.60Astrongdetitanation,asappliedbyRibouretal.withvacuumand

37

elevatedtemperatures(upto140°C)willremovelargeamountsofthetitaniumon
thecatalyst,leadingtoadrasticdropofactivityby80%upto100%.87Moder-
atelyloweringtherelativeamountoftitaniumonthesurfacecouldenhancethe
stereospecificity72orthePDI;88therelativeconcentrationoftheIDisenlarged(it
coordinatesstrongerthantheTispeciestoMgCl2)andthedistributionofactive
siteswillbemorehomogeneous.Dependingontheamount(andtype)ofTispecies
removed,theremightbealoweractivitybutanimproved,morenarrow,PDI.
ApplyinganadditionalwashingstepwithdifferentsolventsonS3(themostactive
sphericalcatalystoftheseries)toreducetheamountoftitaniumwasdeemedsuit-
abletoenhancetheperformance,mostnotablytheinteractionofactivityandPDI.
Suchanactivationprocedurewouldbeabletowashawayresidueofphysisorbed
TiCl4,coordinatedunstableandevenstabletitaniumspeciesstillleftfromprevious
washingstepsappliedduringthecatalystsynthesis.Ifsuccessful,thiscost-effective
approachcouldbeeasilyimplementedinthecatalystproduction.

4.4.1ActivationProcedure

Asoutlinedabove,amoderateactivationprocedurewaschosentoremoveexcess
titaniumwhileinhibitingextremedetitanation.Theexperimentswereconducted
inglassflasksinaninertargonatmosphereusingstandardSchlenktechnique.The
catalystwassuspendedinthesolventandactivatedaccordingtotheparameters
foundinTable4.6.Insteadofagitationwithamagneticstirbartheflaskwas
gentlyshakentoassuremechanicalintegrityofthecatalystparticles.Alternatively,
aSoxhletextractorwastestedfortheactivationprocedure.Aftertheactivation,
thesolventwasremovedandtheactivatedsamplewaswashedthreetimeswith
n-heptaneatRT.Thesamplesweredriedovernightundervacuum(≈1∙10−2mbar)
T.RatTwolinear(n-hexaneandn-heptane)andtwoaromatichydrocarbonsolvents
(tolueneandethylbenzene)werechosenasactivationreagents.TiCl4exhibitsexcel-
lentsolubilityinthesesolventsandtheyarewellavailableinindustry.Twomixtures
oftoluenewithTiCl4(volumeratios1:1and10:1)werealsochosenasactivation
reagentstoinvestigateifthiswouldleadtoahigherhomogeneityofactivesitesand
PDIs.erwlo

38

Table4.6:ActivationConditions

TemperatureTactivation95
SolventvolumeVsolvent250mL
Catalystsampleweightmcatalyst2.5g
DurationΔtactivation90min
Note:Temperaturewas65°Cforn-hexane.

4.5PolymerizationsAfterActivation

Thepolymerizationswereconductedapplyingthesamesetofparameters(seeTa-
ble4.2inChapter4.3)asduringtheinitialtestingofthepurecatalysts.The
preparationofthecatalyst,itsreactionwiththeexternaldonorandtheactivation
withtheco-catalystisidenticaltotheprocedureoutlinedinChapter4.3.1.The
solidburettewasusedfortheinjectionofthecatalyst.

4.5.1CatalystActivity
Thecatalystactivitywasaffectedbytheactivationprocedure;italwaysdropped
belowthevalueoftheunactivatedcatalyst.Asummaryoftheactivitiesandthe
titaniumconcentrationsofallactivatedsamplesislistedinTable4.7.n-Hexane,
n-heptaneandtoluenehavearelativelyloweffectontheactivity;thevaluesremain
within10%deviationoftheunactivatedcatalyst.Theeffectofethylbenzeneonthe
activitywassurprisinglystrong;anactivitylossofmorethan35%wasdetermined.
TheactivitylossescorrelatewiththeTiconcentration(seebelow,Figure4.15).

EffectofActivationDuration
Thedurationoftheactivationinfluencesthedegreeofactivityloss,ascanbe
seeninacomparisonofS3A5(toluene,Δtactivation=30min)andS3A3(toluene,
Δtactivation=90min).Theactivitydrops4.1%and8.2%,respectively.Judging
fromtheTiconcentrationsofS3A5andS3A3(3.8%and3.4%),thedetitanation
isafunctionofcontacttime.

Table4.7:SummaryofCatalystActivitiesAfterActivation

catalystactivationreagentactivityarelativedeviationTiconc.
gkgpolyme∙rhofactivity[wt%]
catalystS3—2.44—4.2
S3A5toluene(30min)2.34−4.1%3.8
S3A2n-heptane2.28−6.6%3.5
S3A3toluene2.24−8.2%3.4
S3A1n-hexane2.22−9.0%3.6
S3A8toluene/TiCl4(10:1)1.84−24.6%2.6
S3A7toluene/TiCl4(1:1)1.72−29.5%2.9
S3A6ethylbenzene1.57−35.7%2.8
S3A4toluene(Soxhlet)0.69−71.7%2.1
Note:Datasortedbyrelativedeviationofactivity.

39

EffectofActivationTemperature
Theactivationtemperaturehasadrasticeffectontheactivity,asitisrevealedbya
comparisonofS3A3(toluene,Δtactivation=90min,,T=95°C)andS3A4(toluene,
Soxhletextraction,Δtactivation=90min,T=111°C/b.p.oftoluene).Theactivity
decreasesby8.2%and71.7%,respectively.TheSoxhletextractionremoved50.0%
ofthetitaniumpresentinS3.Itistobeassumed,thatthedetitanationaccelerates
considerablyatelevatedtemperatures.

EffectofadditionalTiCl4intheActivationReagent
Theadditionofextra-TiCl4leadsaswelltoadecreaseinthetitaniumconcen-
trationofS3A7andS3A8,accompaniedbyadecreaseofactivity.Compared
toS3A3(toluene),thelossofactivityofS3A8(toluene/TiCl4,1:1)andS3A7
(toluene/TiCl4,10:1)wasremarkable.However,ananalysisoftheeffectofthe
activationonthePDIrevealedapositiveeffectoftheadditionalTiCl4(seebelow,
4.5.2).Chapter

40

trationConcenTitaniumwithCorrelationFigure4.15showsadiagramoftheactivityagainstthetitaniumconcentration.A
decreaseoftitanium–asobservedduringallactivationexperiments–leadstoa
decreaseofactivity.Thefittingfunctionisnon-linear.Eachactivationreagent(see
Table4.7)hasacharacteristiceffectonthetitaniumconcentrationandthusthe
.S3ofyactivit

Figure4.15:Activityagainsttitaniumconcentration.

Theactivationexperimentsrevealed,thatS3wasalreadyoptimizedregardingthe
presenceofexcesstitaniumpossiblyinhibitingcatalyticallyactivesites.Activation
–evenforashortduration–alwaysledtoadecreaseofactivity.Thisoriginates
inaremovalofactivetitaniumspeciesbytheactivationreagent.Asimilarremoval
hadalreadybeendescribedbyBrambillaetal.,60buttheyonlyremovedweakly
coordinatedunstablespecieswithn-hexaneatRT.Sincesuchastephadalready
beenconductedduringthecatalystsynthesisofS3,theactivationledtoapartial
removalofstableandactivetitaniumspeciesofS3,downuntil2.1wt%.

MassesMolecularolymerP4.5.2AGPCanalysisofthesynthesizedpolymersrevealedacorrelationbetweentheti-
taniumconcentrationofthecatalystandthepolymerproperties,mostprominent
thepolydispersityindex.Thus,suchpropertiesarealsodependentonthecho-
senactivationreagentandtheactivationconditions.Figure4.16aillustratesthis
correlation:ThePDIvaluesdecreasewiththetitaniumconcentration.Withthe
exceptionofonevalue,aclosetolinearrelationship(seefitline)canbeproposed,

41

consideringthelargemarginoferrorofGPCmeasurements(relativestandardde-
viationof6%to10%forMwaccordingtoMori115).Theactivationprocedurewill
affectthosespeciesfirst,whicharemostweaklycoordinatedtothesupport.As
statedbyStukalovetal.,72theIDcomplexesaremuchstrongerthanthoseofTiCl4.
Thus,theactivationhasagreatereffectonthetitaniumcomplexesthanontheID,
visibleinadecreaseofthetitaniumconcentration.ConsideringtheincreasedID
concentration(relativetoTi),itcanbeassumedthatthedetitanationalsoresults
inamorenarrowvarietyofactivesites.Thisleadstoanarrowingofthemolecular
massdistribution,andsmallervaluesforthePDI.

(a)PDIagainstTitaniumConcentration.

(b)MolecularMassMwagainstTitanium
tration.Concen

Figure4.16:ComparisonofMwandPDIagainsttheTitaniumConcentration.

PlottingthemolecularmassMwagainstthetitaniumconcentration(Figure4.16b)
revealsaninconclusivecorrelation.AsinthecaseofthePDI,alinearfitoftheMw
dataagainstthetitaniumconcentrationappearstobepossible.However,consider-
ingthealreadymentionedlargemarginoferrorofGPCmeasurements,thefluctua-
tionofthevaluesistoolargetoestablishadefinitelinearfitofallvalues.Thereisa
tendencyforMwtodecreasewiththetitaniumconcentrations,adefinitecorrelation
can’tbeestablishedhowever.AsummaryofallvaluesisfoundinTable4.8.

4.5.3StereoregularityDeterminationbyNMRSpectroscopy
IthasbeenpointedoutinChapter2.1.2,thattheremovaloftitaniumspeciesfrom
thesupportsurfaceresultsinanincreasedhomogeneityoftheactivesites,visible

42

Table4.8:SummaryoftheMolecularMassAveragesandPDIsAfterActivation

catalystactivationreagentMnMwPDITiconcentration
molgmolg[wt%]
S3—700002500003.64.2
S3A6ethylbenzene500001900003.82.8
S3A1n-hexane700002400003.43.6
S3A3toluene700002200003.13.4
S3A2n-heptane700002220003.13.5
S3A5toluene(30min)600002000003.33.8
S3A7toluene/TiCl4(1:1)800002400003.02.9
S3A8toluene/TiCl4(10:1)500001400002.82.6
S3A4toluene(soxhlet)600001700002.82.1
Note:DatasortedbyPDI(descending).

inlowervaluesforthePDIandimprovedstereoregularity.Theformercouldbe
shownabove,inChapter4.5.2.Theeffectoftheactivationonthestereoregularity
ofthesynthesizedpolymerscanbestudiedbydeterminingthepentadtacticities
with13C-NMR.30,69,116–119Thecontentofmesopentads(mmmm%)isdetermined
fromthemethylcarbonresonancedatabetween19ppmand22ppm:

mmmm%=(Smmmm/Stotalmethyl)∙100

Smmmmistheareaofthemmmm-pentadmethylpeakat≈21.8ppmandStotalmethyl
isthesumoftheareaofallmethylpeaks.
Incontrasttothedeterminationoftheisotacticityindexandthe“isotactic”and
“atactic”fractionsbydeterminingtheheptane-insolublefraction,120amoredetailed
viewcanbeobtainedwith13C-NMR.Thismethodismoreprecise,asonly90%of
theinsoluble(isotactic)fractionismadeofmmmmpentads.69ObtainingNMRspec-
traofthepolymerssynthesizedfrompureandactivatedcatalysts(S3andS3A1-8,
respectively)provedtobechallengingduetothelowsolubilityofthepolymerin
mostsolvents.Asuitableprocedureallowingthe13C-NMRanalysisincludeddis-
solvingthepolymerin1,2,4-trichlorobenzene(TCB)anddimethlysulfoxide-d6(5:1
volumeratio)atT=410Kwithapolymerconcentrationofca.100mgmL−1.How-

43

ever,theprobeheadoftheNMRspectrometerused(seeChapter6.2.4)couldnot
beoperatedatsuchatemperatureforasufficientlylongtime.Thedataacquisition
waslimitedto1024scanstoensuretheintegrityoftheprobehead.Theaccompa-
nieddecreaseinresolutionresultedinspectrainwhichonlystrongsignalscouldbe
detected.ThepolymerssynthesizedlaterinChapter5,exhibitseveralsuchstrong
peaksinthemethylregion,correspondingtodifferentpentads.However,inthecase
ofallpolymerssynthesizedfromS3andS3A1-8,onlythesignalcorrespondingto
themmmm-pentadcouldbedetected.Figure4.17showsthemethylregionofthe
13C-NMRspectrumofS3A4.

Figure4.17:Representative13C-NMRspectrum.Displayedistherelevantmethyl
region(ca.21.6ppm–19.7ppm)ofS3A4.Onlythemmmm-pentadatδ=
21.61ppmisvisible.

Arithmeticallyspeaking,withmmmm%=100,thepolymersarecompletelyiso-
tactic.However,duetothemarginoferror,resultingfromthelowresolution,the
polymersshouldratherbereferredtoas“highlyisotactic”.Asaconsequence,it
isnotpossibletoestablishacorrelationbetweenthe13C-NMRdata,thetitanium

44

concentrationandthepolymerproperties(MwandPDI).Theliteratureaboutsim-
ilarexperiments88suggests,thattheisotacticityofthepolymerimproveswhena
decreaseofthePDIisobserved.

4.6VideoMicroscopyPolymerization

Polymerizationsinaconventionalautoclavesetupdonotofferadirectobservation
oftheevolutionoftheparticlemorphologyofasingleparticle.Whereasthecatalyst
activitycanbeobservedonlinethroughtheconsumptionofmonomeranddisplayed
inamonomer-flowdiagram,thepolymergrowthonthecatalystparticlecannotbe
observedonlineinasystemclosedtoanobservationfromtheoutside.
ThisissuewasfirstaddressedbyReichertandcoworkersinthepolymerization
ofbutadiene,byintroducingthevideomicroscopy,amethodtoobservesinglerest-
ingpolymerizingparticlesinasmallgas-phaseautoclaveequippedwithamicro-
scope.121–125Weickertetal.andFinketal.alsoexaminedolefinpolymerizations
withvideomicroscopy.126–128Videomicroscopyexperimentswereconductedwith
S3togaininsightintothepolymerizationbehavior(especiallyreplication)during
polymerizationandtotestanindirectmethodofactivationwiththeco-catalyst.

4.6.1ExperimentalPreparationandAnalysis
Adetailedpresentationofthevideomicroscopyequipmentandtheexperimental
setupisfoundinChapter6.2.2.Thereactionconditionswereaimedtobesimilar
tothecorrespondingslurrypolymerization:

Table4.9:VideoMicroscopyPolymerizationConditions

TemperatureT70
Propylenepressureppropylene5.00bar

Toachievesingleparticleobservation,onlyafewgrainsofthecatalystwere
dispersedontopofthesampleholder.Duetothehighsensitivitytowardswaterand
oxygen,thepreparationhadtotakeplaceinsideaglovebox.Adetailedsummary
oftheprecautionstakenarefoundintheexperimentalsection(Chapter6.3.3).As

45

opposedtoKnokewhoactivatedthecatalystinhisPh.D.dissertationdirectly,128
itwasattemptedtoactivatethecatalystindirectly.Adirectcontactbetweenthe
catalystandtheco-catalyst/externaldonorwetsthesampleandnecessitatesan
additionaldryingsteppriortopolymerization.Therefore,thealuminumalkyland
thesilanewerebroughtintothebottomoftheautoclave.Theactivationtookplace
byevaporatingco-catalyst/externaldonorwhilethereactorwasheatedtoreach
polymerizationtemperature.Initialdifficultiesarisingfromthecondensationof
liquidontheinnersideofthewindowwereovercomebyheatingthewindowfrom
outsidewithhotair.Duringthepolymerization,micrographsweretakenevery30
seconds,beginningwhenthereactorreached70.Thereactionwassubsequently
stoppedbydepressurizingthereactorandflushingwithargon.
UsingImageJ,themicrographswerepreprocessedwithathresholdingalgorithm
andtheareaAofeachparticle’sprojectionwasmeasured.Theobtainedvalues
werethenconvertedtocircle-equivalentdiameters(CED):
CED=2∙A(4.7)
πTheCEDcanbeusedtofurthercalculatethesphere-equivalentvolume(SEV):
SEV=π∙(CED)3(4.8)
6ThevalueswerethennormalizedwiththeinitialCED0andSEV0,respectively.

4.6.2VideoMicroscopyPolymerizationofS3
Propylenewaspolymerizedfor20minaccordingtotheparametersoutlinedabove.
AselectionofsixmicrographsatdifferentpointsintimeisshowninFigure4.18a–
4.18f.Thepolymerizationwasstoppedafter20minduetoincreasedblurringofthe
images,prohibitinganexactanalysisoftheparticleproperties.Theblurringwas
causedbythepropyleneandtheevaporatingco-catalyst/externaldonormixture
flowinginsidethereactor,resultinginchangingrefractionindicesinthelineofsight.
Ascanbeseenfromtheselectedmicrographs,aparticlegrowthwasvisible.Atthe
sametime,itcanbeseen,thatnotallparticlesparticipatedinthepolymerization.
Thus,theobservationwasconfinedtotheparticleslabeled1through5.Figure4.19
containstwodiagrams,showingthecourseofthenormalizedCEDandSEVvalues
againstpolymerizationtimefortheselectedparticles.

46

(a)

(c)

t

t

==08minminFigure

Figure

t(b)

4.18

t(d)

4.18

==4min12min

16=t(e)min

(f)t=20min

47

Figure4.18:Catalystparticles,observedatdifferentpointsoftimeduringpoly-
merization.Fiveparticleshavebeenmarked,observedandanalyzedforpolymer
wth.gro

(a)NormalizedCEDvaluesforparticles1-5.

(b)NormalizedSEVvaluesforparticles1-5.

Figure4.19:NormalizedCEDandSEVvalues,showingthegrowthoftheobserved
particles.single

48

Theparticlesdidnotbegintopolymerizeatthesametime.1,2and3began
polymerizingfromthestart(i.e.,whenthereactorreached70).1and2polymer-
izedatthesamespeed(indicatedbysimilarslopes),thegrowthof3wasslower.The
initialparticlegrowthwasquitefast,sinceinitiallyformedpolymerfractionatedthe
catalyst,givingthemonomeraccesstomoreactivesites(pleaseseeChapter2.1.4for
anintroductiontothephenomenaoffragmentationandreplication).Thecatalyst
surfacewasthencoveredbyanincreasinglayerofpolymer,inhibitingthediffusion
ofthemonomertotheactivesites.Thespeedofpolymerizationdecreased,made
evidentinaflatteningofthegraphs.Ultimately,thepolymerizationstopped.The
dentinthegraphof3at12minwascausedbytheparticletiltingover,presenting
aslightlysmallerprojectionarea.4and5begantopolymerizeafter15minand
10min,respectively.Theinitialspeedofgrowthwassimilarto1and2.
Thereplicationofthecatalystmorphologywasnothomogeneous,ascanbeseen
inacomparisonof1,2and3atthebeginningandtheendofthepolymerization
(Figures4.18aand4.18f,respectively).Thepolymergrowsinhomogeneously,not
replicatingtheinitialshapeofthecatalyst.4and5ontheotherhand,replicate
e.shapcatalysttheTheindirectactivationofaZiegler-NattacatalystlikeS3shouldnotbepreferred
toadirectactivation.Eventhoughiteliminatestheadditionalstepofcontacting
thecatalystwiththeco-catalyst/externaldonormixture,followedbydryingprior
tothepolymerization,theexperimentalresultsindicateadeficientactivation.The
catalystparticlesdonotbegintopolymerizeatthesametime,exhibitalowreplica-
tionperformanceandquicklydeactivate.Theactivationisdependentonasufficient
amountofco-catalyst/externaldonoronthecatalyst.AsalreadyhintedatbyWei-
ckertetal.,thealuminumalkylhasalowvaporpressure,126thusinhibitingsufficient
contactwiththecatalyst.Theexperimentaldatanowrevealsthatthedistribution
oftheco-catalyst/externaldonorintheproximityofthecatalystisinsufficientwhen
activatingindirectly,impedingasatisfactorypolymerizationperformance.

5Chapter

NovelMethodfortheSynthesisof

ortsSuppCatalyst

erviewOv5.1

AnovelmethodforthesynthesisofaMgCl2-basedcatalystsupporthasbeende-
veloped.Sphericalparticlesweregeneratedbyacontrolledassemblyofmicroscaled
submoieties.Thefinalparticleshadanarrowparticlesizedistributionandhigh
porosity.Threecatalystswerepreparedfromsaidparticles,withandwithoutan
additionaldonor,havinggoodstereoregularitybutlowactivityinpropylenepoly-
merizations.

5.2SupportPrecursorSynthesis

Initial5.2.1tsThough

Nowadays,synthesisroutesforMgCl2-basedcatalystsupportmaterialsaimatthe
directformationoffinalparticles.57,58,129–134However,precisemorphologicalcontrol
isachievedonlyonamicrometerscaledlevel.Propertieslikesurfaceareaand
porosityaredifficulttofine-tune.Consequentially,developingamethodthatoffered
ahigherdegreeofmorphologicalcontrolwasaninterestingchallenge.Theidea
devisedfromthisincentivecomprisedthesynthesisofnano-ormicrometersized
submoietiesandtheircontrolledassemblytolarger,finalsupportparticles.Such
anapproachwouldenablemorphologicalcontrolonasmallerscalethancurrently

49

50

feasible.ThedevelopmentofthenovelmethodforthesynthesisofaMgCl2-basedcatalyst
support,presentedinthiswork,wasinfluencedbytheso-calledPILPprocessin
biomineralization:InstudiesbyGowerandTirrellitwasshownthatlowmolecu-
larmasspolypeptidescanalterthecrystallizingenvironmentofcalciumcarbonates
inaqueoussolutionsbyinducingaphase-separationofahydratedcalciumcarbon-
ate/polypeptideliquid-precursorphase.135GowerandOdomlaterproposed,that
thesolutioncrystallizationprocessistransformedtothepolymer-inducedliquid-
precursor(PILP)process,asolidificationprocessofaliquid-phasemineralprecur-
sor,inwhichitcanbedepositedonsubstratestoproducemineralfilmsorspatially
limitedstructures.136ThePILPprocessenablesthesynthesisofcrystallinenon-
equilibriummorphologiesresemblingsolidifiedmeltsorliquidcrystalsastheyform
fromafluid-likeprecursorstateandaimatacontrolledmineralizationwithhigh
morphologycontrolanduniformcrystallization.Asaforementioned,morphology
controlisahighlysoughtafterfeatureinthesynthesisofZiegler-Nattacatalyst
supports,andtheperformanceofthePILPprocessinthisregardisintriguing.
However,sinceMgCl2ispronetoformhydrates,unwantedinZiegler-Nattacatalyst
supports,thetargetedsynthesisprocedurewasconfinedtoanon-aqueousenviron-
ment.Asaresult,thePILPprocesshadtobemodifiedtosuittherequirements.It
wasintendedtogeneratenano-ormicrometerscaledsubmoieties(“microparticles”
inFigure5.1)andassemblethemwithhighmorphologicalcontrol,usingbinder
molecules,yielding“macroparticles”suitabletobeusedasZiegler-Nattacatalyst
orts.supp

Figure5.1:Initialthoughtsofaformationofmacroscaledparticlesthroughacon-
trolledassemblyofmicroscaledsubmoieties.

TheMgCl2-basedsupportmaterialobtainedthroughsuchanovelsynthesismethod

hadtomeetcertainrequirements,asoutlinedinTable5.1

Table5.1:RequirementsforaZiegler-NattaCatalystSupport

sphericalshapehighsurfacearea
suitableparticlesize(15µm...80µm)137,138MgCl2intheactiveform
distributionsizeparticlewnarro

51

PreparationtationerimenExp5.2.2OfthemultitudeofpossibilitiesfortheMgCl2tobegeneratedintheactiveform(see
Chapter2.1.2),fast-solidificationfromMgCl2-ethanoladductswaschosen.Itwas
deemedtobethemostsuitableapproach,beingsuperiortoanin-situMgCl2forma-
tionviathechemicalroutebecausetheadductcouldbepreparedinaseparatestep,
precedingthesupportparticleformation.Theseparationoftheadductsynthesis
andtheactualparticleformationsimplifiedcontrolovertheentireprocedure.
AnhydrousMgCl2,itsalcoholadductsandespeciallythefinalsupportparticles
(duetotheirhighsurfacearea)areverysensitivetomoisture.Inaddition,thefinal
Ziegler-Nattacatalystisalsoverysensitivetowardsoxygen,becauseitdeactivates
theactivetitaniumspecies.139Therefore,allcomponentsofthesynthesisandall
materialswerethoroughlydriedpriortouseandtheexperimentationtookplacein
aninertgas(argon)environment.Schlenktechniquewasappliedforthehandling
ofallcomponentsandmaterials–agloveboxwasusedwhennecessary.
Experimentationinglassapparatusesprovedtobeunsuitable:TheMgCl2-ethanol
adductsandlaterinterstageproductsadheredtotheglassbecauseofitsOH-
functionality,hinderingeffectivemixingandhandling(Figure5.2a).Thisbehavior
wascounteredbyahydrophobizationoftheglasssurfacewithtrimethylchlorosilane
(Figure5.2b),greatlyloweringtheabilityofthereactantstosticktothewall.
However,evenmoreproblematicprovedtobetheeffectiveagitationofthere-
actants.Theonlystirringmethod,thatwasavailableforSchlenkvesselswasa
magneticstirbar.Buttheshearenergyneededforaneffectiveparticledispersion
couldnotbebroughtintothesysteminthisway.Forthesereasons–afteraseriesof
experimentsinglassapparatuses–allsynthesisstepsweresubsequentlycarriedout

52

(a)Schlenktubewithadhering
adducts.-ethanolMgCl2

(b)Hydrophobizationoftheglasswallswith
hlorosilane.ylctrimeth

Figure5.2:Silane-modificationofglassequipment.

inasteelautoclave.TheMgCl2-ethanoladductsandlaterinterstageproductsdid
nolongeradheretothereactorwalls.Themagneticallycoupledbladestirrerofthe
autoclaveprovedtobeaveryeffectivemethodforintroducinghighshearenergy
withoutcompromisinginertgasconditions.Additionally,theautoclave’sdouble-
mantledesigninconjunctionwithanattachedcryostatofferedexcellenttempera-
turecontrol.Italsoturnedoutthatthereleasevalveatthebottomoftheautoclave
wasveryusefulforaquickreleaseandsubsequentsolidificationofthereactants.

5.2.3NovelSynthesisMethod

ThestartingmaterialforallsupportsynthesisexperimentswasMgCl2-ethanol
adduct.Thus,precedingeverysubsequentstep,anhydrousMgCl2wasreactedwith
dryethanoltoyieldtheadductMgCl2(EtOH)2(N1).

Figure5.3:Synthesisoftheethanoladduct.

53

TheMgCl2wasbroughtintotheautoclave,towhichwaschargedparaffin.The
suspensionwasstirredataspeedof400rpm.Dryethanolwasaddedtothesuspen-
siondropwiseatRT.ThemixturewasstirredatRTfor10minfollowedbyheating
to70for2htoformN1stoichiometrically.Thenthemixturewasallowedtocool
downtoRTundermechanicalagitation.1-DecanolwasaddedtotheslurryofN1
inparaffin,andthemixturewasstirredat70for1h,followedbycoolingdown
toRTtogiveN3.

Figure5.4:Synthesisofthe1-decanoladduct.

N3hastobeconsideredanon-stoichiometricnetworkasindicatedbythe“x”
intheformulaofScheme2.Asasimplification,N3isconsideredtobeamixture
ofN1andN2asshowninChart1(Figure5.5).TheabilityofN2toactasa
surfactantisevident.Thelonglinearcarbonchainofthe1-decanolishydrophobic,
whereastheMgCl2-ethanol“head”ismorehydrophilic.

Figure5.5:SimplifiedillustrationofN3,beinganon-stoichiometricnetworkofN1
.N2and

Ascanbeseeninverificationexperiments(seeChapter5.4.1),N3willformsmall
micrometerscaleddropletsatthisstageduetotheseanchoredalcohols.
Poly(ethyleneglycol)200(PEG-200)wasaddedtoN3atRT,yieldingN4,an
aggregationofdroplets.AnagainsimplifiedproposalofthepossiblestructureofN4

54

isgiveninScheme3(Figure5.6).ThecoordinationbehaviorofthePEG-200cannot
bepredictedprecisely.Itcaneitherbindotheradductstogether(likeacement)or
coordinatetoonlyonespecies.

Figure5.6:SimplifiedillustrationofN4.

N4inparaffinwasstirredat70for30minandwasfinallymeltedat130
undervigorousmechanicalagitation(800rpm).Themechanicalstirringdispersed
themoltenMgCl2adductsintodroplets.After30min,thereactorcontentwas
quicklyreleasedviathebottomvalveoftheautoclaveandpouredintoalarge
amountofpre-cooled(−50°Cto−40°C)dryn-pentaneinaSchlenkflask.The
liquiddropletsofMgCl2adductssolidifiedtoformsphericalparticles(N5).Ascan
beseenfromSEMimages(Figure5.7),N5consistsofperfectlysphericalparticles.
AccordingtoaPSDanalysis(Figure5.7b),themodalvalueofthediameteris
xa,max=58µm,themedianx50=58µm.
ItcanbeseeninFigure5.7d,thatN5isbuildupfromsmallerparticles.The
complexsurfacestructuresuggestsahighsurfaceareaand–afterdealcoholation–
ahighporosity.Accordingtotheamountofstartingmaterial,a“yield”of48%
canbedetermined.Theweightlosscanbeattributedtothestructuralchangesof
themixtureatelevatedtemperaturesatwhichethanolcanevaporate.Thispar-
tialevaporationisaccompaniedbyanincreaseofthemeltingpointoftheadduct
mixture,thusleadingtoadesirablefastersolidification.
Measuringthesurfaceareaand/orporositywasnotpossiblewiththeavailable
equipment.Eventhoughutmostcareandveryfastoperationwereapplied,the
sampleshydrolizedduringeachanalysis,causinghighlyfaultyresults.Thus,the
porosityandsurfaceareacouldonlybejudgedqualitativelyasbeing“large”.This
assumptionisbackedtoacertainextentbytheobtainedSEMimagery.

(a)SEMimageofN5.

(c)SEMcloseupimageofN5.

5.7:FigurehericalSp

.N5ofPSD(b)

SEMofsectionMagnified(d)

catalystsupportprecursorN5.

55

image.closeup

56

Dealcoholation5.3

Judgingfromthevisualimpression,N5isasuitablesupportmaterialforZiegler-
Nattacatalysts.However,itisstillaprecursor.Thealcoholshavetoberemoved
priortocatalystsynthesis,otherwisetheTiCl4wouldformcatalyticallyinactive
alkoxideswiththealcohols.54Severalmethodsforthedealcoholationofsuchsup-
portprecursorsareknown.Theycanbecategorizedinthermal140andchemical
treatments.54Whereastheformeristargetedtoaremovalbyevaporationofthe
alcohols,thelatterchemicallymodifiesthealcoholstobelaterremovedortobein-
activatedtowardsTiCl4.54Variantsofbothmethodshavebeenappliedand–where
necessary–adaptedforthespecificneedsoftheprecursor.

DealcoholationThermal5.3.1

DealcoholationThermalacuumVunder

AsampleofN5wassuspendedinn-decaneandheatedupto50undervacuum
(approx.8∙10−3mbar)for2h.Theyieldedproduct(N6)wasfilteredoff,washed
withn-pentaneanddriedundervacuum(≈1∙10−2mbar).Aweightlossof13.8%
wasdetermined.AscanbeseeninFigure5.8a,N6lostitsmacroscaledspherical
morphology.Figure5.8bshowsamacroparticlewhichwasstillsphericalinshape.
Itcanbeseenthatitismadefromsmallerparticles.

(a)

(b)

Figure5.8:SupportN6(precursorN5,thermallydealcoholatedundervacuum).

57

ThermalDealcoholationinanArgonStream
AsampleofN5wasbroughtintoaSchlenkfrit.Astreamofargonwasheated
upto70bylettingitflowthroughcoppertubing,submergedinanappropriately
heatedoilbath.TheargonwasattachedtotheSchlenkfritandthesamplewas
driedfor2h,yieldingN7.Aweightlossof9.5%wasdetermined.Itcanbeseenin
Figure5.9thatthemacroscaledmorphologyismostlypreserved.However,acloser
inspectionrevealedastrongsmoothingofthesurface,attributedtoadegradation
.morphologynanoscaledtheof

Figure5.9:SupportN7(precursorN5,thermallydealcoholatedinaninertgas
stream).

DealcoholationChemical5.3.2ChemicalDealcoholationwithTetrachlorosilane
AsampleofN5wassuspendedinn-heptaneandcooleddowninanicebath.
Tetrachlorosilane(SiCl4)wasadded,generatingHCl.Thesuspensionwasgently
shakenuntilthereactionwasover.Theliquidwassiphonedoffandwashedwith
n-pentane.Theproductwasthendriedundervacuum(≈1∙10−2mbar),yielding
N8.Aweightlossof15.0%wasdetermined.ApplyingSiCl4toremovethealcohol
hasafavorablesideeffect.AsshowninScheme4(Figure5.10),itreactswith
thealcohols,formingalkoxysilanes,whichcanactasastereoregulatingdonor(see
Chapter2.1.2).Thealkoxysilanesremainonthesupportuntilfurthertreatment
.TiClwith4

58

Figure5.10:ReactionofN5withSiCl4.

Themacroscaledmorphologywaspartiallylost,asapparentfromFigure5.11.
Manyparticlesbrokeinhalf,theyseemedtohavebecomeverybrittle.Theparti-
clesshowahigherporositywhileretainingnanoscaledintegrity,suggestingasuc-
cessfuldealcoholation.AnobservationofbothFigure5.11aand5.11bsupportsthe
assertionthatN5reallyisassembledfromsmallparticles.N8waschosenforasub-
sequentcatalystpreparation(seeChapter5.6),becauseitlargelykeptitsmacro-
.morphologynanoscaledand

(a)

(b)

Figure5.11:SupportN8(precursorN5,chemicallydealcoholatedwithSiCl4).

ChemicalDealcoholationwithTrimethylchlorosilane
Trimethylchlorosilanewaschosenasavariantincomparisontotetrachlorosilane.In
contrasttoSiCl4,thereactionhadtobeheatedinsteadofcooledforthereactionto
takeplaceatadecentspeed.AsampleofN5wassuspendedinn-heptane.After
theadditionoftrimethylchlorosilanethesolutionwasheatedto70for4.5hand

59

gentlyshaken.Themixturewaswashedat70withn-heptane.Theproductwas
thendriedundervacuum(≈1∙10−2mbar),yieldingN9.Aweightlossof21.3%
wasdetermined.AscanbeseeninFigure5.12a,N9largelylostitsmacroscaled
sphericalmorphology.Figure5.12bshowsamacroparticlewhichwasstillspherical
inshape.SimilartoFigure5.11b,itcanbeseenthatthesupportismadefrom
smallerparticlesandhasaporousstructure.

(b)(a)Figure5.12:SupportN9(precursorN5,chemicallydealcoholatedwithClSi(Me)3).

5.4VerificationExperiments
Inordertoinvestigatethedifferentfunctionsof1-decanolandPEG-200,andtoshow
thedependencyoneachother,aseriesofverificationexperimentswereconducted.
Inthecourseofexperimentationitbecameevidentthatthepresentedsynthesis
procedureisverysensitivetotheamountofthereactantsusedandtotheparameters
chosen.Subsequently,aseriesofexperimentsispresented,inwhichdifferentalcohols
and/orpolymerbinderswereused.

l1-Decano5.4.1TheparticlesinFigure5.14aand5.14bwereproducedbyreactingN1with1equiv-
alentof1-decanolinparaffin(seeScheme5inFigure5.13).Themixturewasstirred
at130undervigorousmechanicalagitationandwasthenquicklypouredintoa
largeamountofpre-cooleddryn-pentaneatca.−45°C,yieldingN10.A“yield”

60

of79%wasdetermined.Thefigureclearlyshowsthatlotsofchunks,havingan

irregularshape,wereformedandthattheprecursorhasnosphericalmacroscaled

morphology.However,acloselooksuggeststhatthesechunksarecomposedofsmall

sub-particlesinasizeofonlyseveralmicrometers(Figure5.14b).Thesesmallpar-

ticlesaggregatewithoutcontrolandaresensitivetomoistureintheair.Amixture

ofN1and1-decanolalonewillnotgeneratesphericalsupportprecursorparticles.

However,thefindingsindicatetheformationofsub-particles,

bled

to

form

macroscaled

particles.spherical

Figure

5.13:

thesisSyn

of

.N10

hwhic

can

eb

assem-

(a)

(b)

61

Figure5.14:SupportprecursorN10(fromthereactionofN1with1-decanol).

PEG-2005.4.2

AdductN1wasreactedwith0.34equivalentsofPEG-200inparaffin(seeScheme6in
Figure5.15),yieldingN11.A“yield”of83%wasdetermined.Irregularchunkswere
producedalmostexclusively(Figure5.16aand5.16b).UnlikeN10,thesechunks
showasmoothsurfacestructureandseemnottoconsistofsmallsub-particles.This
isconsistentwiththestrongercoordinatingabilityofPEG-200toMgCl2asopposed
tothatof1-decanolduetotheexistenceofmultielectrondonorsinthebackbone
ofPEG-200.AmixtureofN1andPEG-200aloneyieldssmoothparticlesofhighly
irregularshapeandsize.Thesmoothsurface,attributedtothestrongcoordination
behaviorofthePEG-200,indicatestheabilityofPEG-200tobindN1strongly
together.ItisthusconsideredacementforN1.

Figure5.15:SynthesisofN11.

62

(a)

(b)

Figure5.16:SupportprecursorN11(fromthereactionofN1withPEG-200).

5.4.3Variationofthe1-Decanol/PEG-200Ratio

Thecorrectmolecularratioofthereactantsis–besidesthereactionparameters–
thekeytoanefficientsynthesisofN5.Aslightdeviationoftheidealratioleads
tounsatisfactoryresults.Thesensitivityofthemethodtothereactantratiois
demonstratedinthesynthesisofN12-N15.TheratiosusedarefoundinTable5.2.
TheidealratioofN5isalsoindicated.SEMimagesofN12-N15(Figure5.17a-
5.17d)reveal,thatslightdeviationsoftheidealratiohaveastrongeffectonthe
particlesandleadtoirregularmorphologies.The“yields”ofN12-N15were81%,
76%,49%and79%,respectively.

Table5.2:VariationofReactantRatios

PEG-200DecanolEtOHMgPrecursorN51:2:0.4:0.11
N121:2:0.3:0.11
N131:2:0.5:0.11
N141:2:0.4:0.06
N151:2:0.4:0.21

(a)SEMimageofN12.

(c)SEMimageofN14.

(b)SEMimageofN13.

(d)SEMimageofN15.

Figure5.17:Supportprecursors,madefromdifferentreactantratios.

63

64

5.4.4VariationoftheReactionTemperature
Afterdeterminingthesynthesismethod,yieldingN5,itbecameevidentthatthe
reactiontemperatureofthefinalparticleformingstepisveryimportant.Thiscanbe
seeninFigure5.18.N16waspreparedusingexactlythesameamountsofreactants
andthesamesetofparameterswiththeexceptionofsaidtemperature.Forthe
synthesisofN16,thetemperaturewasloweredfrom130to125.A“yield”of
54%wasdetermined.Althoughmanysphericalparticleshavealreadybeenformed,
itcanbeseenthatthisfinalstepisstillincompleteduetothelowertemperature.

Figure5.18:SEMimageofN16.

5.4.5VariationoftheAlcoholsandBinder
TheidealsystemforthenovelsynthesismethodisMgCl2/ethanol/1-decanol/PEG-
200,whichhasbeenusedforN5.Inaddition,avarietyofdifferentreagentshave
beentestedfortheparticlesynthesistoreplacetheshortchainalcohol,thelongchain
alcoholandthepolymer“binder”.Table5.3listsanoverviewoftheexperiments
withvaryingreagents.Theexperimentswereconductedusingthesetofparameters
knowntoyieldsphericalsupportprecursors(N5).

1-Octanol

Themostpromisingreplacementwas1-octanolinsteadof1-decanolasthelongchain
alcohol.However,itwasnotpossibletogenerateparticlesusing1-octanolhaving
morphologicalpropertieslikeN5.AnSEMimageofthebestexampleofasupport

Table5.3:VariationofReactants

Precursorshortalcohollongalcoholbinder
PEG-2001-decanolethanolN5PEG-200ctanol1-oethanolN17N18methanol1-decanolPEG-200
PEG-4001-decanolethanolN19PPG-4251-decanolethanolN20N211-propanol1-decanolPEG-200
PDMS1-decanol1-propanolN22olyTHF-250P1-decanol1-propanolN23

65

precursorsynthesizedvia1-octanol(N17)ispresentedinFigure5.19(“yield”:40%).
Thegeneratedparticlesarefairlylarge,withaveragediametersbetween100µmand
150µm.Itcanbeseen,thatpartsoftheadductwereunabletoattainaspherical
macroscaledshape.ThesurfacestructureissimilartoN5,withsubstructuresvisible
surface.theon

(a)

(b)

Figure5.19:SEMimageofN17.

66

MethanolReplacingethanolwithmethanoltoformtheprimaryMgCl2adductwasunsuccess-
ful.ItwasnotpossibletosolidifytheadductmeltofMgCl2/methanol/PEG-200.
Onlyawaxysubstance(N18)wasyielded,havingnoparticulatemorphology.

Poly(ethyleneglycol)-400
Poly(ethyleneglycol)-400(PEG-400)waschosentoinvestigatetheinfluenceofthe
binderontheformationofthesupportprecursor.PEG-400issimilartoPEG-200,
butitsaveragemolecularmassistwiceashigh(400gmol−1,n=8or9inChart2b,
seebelow).TheSEMimages(Figure5.20aand5.20b)ofasupportprecursorsyn-
thesizedwithPEG-400asabinder(N19)show,thattheformationofmacroscaled
particlesoccurs(“yield”:51%).However,alargeportionoftheMgCl2/ethanol/1-
decanoladductwasnotbroughtintothedesiredmacroscaledsphericalshape.

(a)

(b)Figure5.20:SEMimageofN19.

Poly(propyleneglycol)-425
Poly(propyleneglycol)-425(PPG-425)waschosentoinvestigatetheinfluenceof
thebinderontheformationofthesupportprecursor.PPG-425isamixtureof
PPGswithanaveragemolecularmassof425gmol−1.Thepredominantspeciesof
PPG-425andPEG-200areshowninChart2(Figure5.21).Theformerhaseight
oxygenatomsinthebackbone,thelatterhasfive.Eventhoughtheoxygenatomsin

67

thebackboneofthePPGareslightlystericallyhinderedduetothemethylgroups,
comparedtoPEG,itwasexpectedtohaveagoodcoordinationabilitytotheMgCl2
adductsandtobeagoodbinder.TheSEMimages(Figure5.22aand5.22b)of
asupportprecursorsynthesizedwithPPG-425asabinder(N20)show,thatthe
formationofmacroscaledparticlesoccurs(“yield”:66%).Itisevenwellvisiblein
Figure5.22bthatthelargeparticlesarebuiltfromanaggregationofsmallersub
particles.However,alargeportionoftheMgCl2ethanol1-decanoladductwasnot
broughtintothedesiredmacroscaledsphericalshape.

Figure5.21:Predominantspeciesofpoly(propyleneglycol)-425andpoly(ethylene
glycol)-200/400.

(a)

(b)

Figure5.22:SEMimageofN20.

68

glycol)-200yleneoly(ethP1-Propanol,

Itwasalsoinvestigatedtoreplaceethanolby1-propanoltoformtheprimary
MgCl2adduct.Theresultsofthesupportprecursorsynthesiswith1-propanol/1-
decanol/PEG-200(N21)seemedpromising(“yield”:72%).SEMimagesofN21
aredisplayedinFigure5.23aand5.23b.ThecloseupimageofN21(Figure5.23b)
revealssinglesphericalparticleswhichconsistofaveryhomogeneousassemblyof
smallersubparticles.Thisisvisibleontheedgesofthecrackedopenparticles.Yet,
themajorityofthereactantswereunabletobeassembledtolargemacroscaled
particles.

(a)

(b)

Figure5.23:SEMimageofN21.

1-Propanol,Poly(dimethylsiloxane)

HydroxylterminatedPoly(dimethylsiloxane)(PDMS)wasusedwiththeMgCl2/1-
propanol/1-decanoladducttoinvestigateitsroleasabinder.AnamountofPDMS
waschosentohaveapprox.thesamequantityofoxygenfunctionalitiespresent.The
resultofthesupportprecursorsynthesis(N22)wassimilartotheotherexperiments
presentedabove(“yield”:62%).AscanbeseeninSEMimages(Figure5.24aand
5.24b),eventhoughsomemacroscaledparticleshaveformed,mostofthereagents
arestilllooselydispersedasuncontrolledagglomerates.Thefewsinglemacroscaled
particleswerebuiltupfromsmallersubparticleshavinganoblong,plate-likeshape.

(a)

(b)

Figure5.24:SEMimageofN22.

1-Propanol,ydrofurane-250olytetrahP

69

ReplacingthebinderwithPolytetrahydrofurane-250toassembletheadductMgCl2/1-
propanol/1-decanolwasunsuccessful.Itwasnotpossibletosolidifytheadductmelt
ofMgCl2/1-propanol/PolyTHF-250.Onlyawaxysubstance(N23)wasyielded,
havingnoparticulatemorphology.

5.5ProposedCompositeFormationMechanism

Basedontheexperiments,amechanismisproposedforthesphericalparticlefor-
mation,describingtheformationofcompositesofliquidinorganicsandpolymers
(CLIP).Aspresentedabove,anhydrousMgCl2reactedwithethanoland1-decanol
successivelyinparaffin,yieldingN3.N3isconsideredanon-stoichiometricnet-
workoftheadductsMgCl2(EtOH)2(N1)andMgCl2(EtOH)2(C10H21OH)(N3),as
illustratedinChart1(Figure5.5onPage53).ApartofN3furtherreactedwith
PEG-200givingamixture,whichcontainsaseriesofadductsinanequilibrium
(N4)becauseofthecomplicatedcoordinationbehaviorofPEG-200.Asimplified
illustrationofthisequilibriumisshowninScheme3(Figure5.6onPage54).
Duringtheincreaseoftemperatureundervigorousmechanicalagitation,themix-
tureofN3andN4(orpartofthismixture)wasmeltedanddispersed,whichled
totheformationofprimarysphericalcomposites(Chart3inFigure5.25).Such
primarycompositeswerestabilizedinthehydrocarbonsolventparaffinbythelong

70

carbonchainanchoredonadductN2.Insidethesecomposites,thereweremainly
aggregatesofthehydrophilicadductN1whichpreferstostayawayfromthenon-
polarsolventparaffin.ThechainofPEG-200,havingbothhydrophilicoxygenatoms
andhydrophobicethylenemoieties,caneitherpenetratethroughsomecomposites
orattachtothesurfaceofthesecompositesandbehaveasa“tentacle”.Sucha“ten-
tacle”hasastrongabilitytograspotherprimarycompositeslikeabindertoform
themacroscaledfinalsphericalcompositeasillustratedinChart4(Figure5.26).
Uponrapidheatdissipation,theshapeofthesefinalcompositeswasfrozenand
MgCl2-basedsphericalcatalystsupportprecursorsweregenerated.

Figure5.25:Primarysphericalcomposites.

Thegenerationofthecompositesofliquidinorganicsandpolymers(CLIP)during
thelaststageofthesynthesisisthespecificcharacteristicofthenovelsynthesis
method.TheCLIPmethodyieldssphericalsupportprecursorparticles,having
anarrowparticlesizedistributionandpresumablyalargesurfaceareaandhigh
porosity.Theprecursorsweredealcoholatedtobeusedascatalystsupports.Actual
catalystsynthesesandpolymerizationexperimentsarepresentedinthefollowing
hapters.c

Figure

5.26:

Macroscaled

final

spherical

comp

osite.

71

72

thesisSynCatalyst5.6

InordertoinvestigatetheperformanceoftheCLIPmethodtogeneratematerials
whichcanbeusedasZiegler-Nattacatalystsupports,threecatalystshavebeen
synthesized.Theapproachissimilartothatfoundinalargevarietyofscientific
publications.47,141–144ThesuitablecatalystsupportswereimpregnatedwithTiCl4
at−20°Candreactedfor2h.InthecaseofN25andN26,theprecursorswere
suspendedinn-heptanepriorimpregnationwithTiCl4.Thereactantswerethen
heatedtoroomtemperatureandtheliquidwasdecanted.AmixtureofTiCl4and
n-decanewasthenaddedtothecatalystforfurtherreaction.Thereactantswere
thenheatedto40°Canddiisobutylphthalate(internaldonor)wasadded.After
30min,thereactantswerethenheatedupto100°Cfor2h.Intheend,thefinal
catalystwaswashedwithn-pentaneanddried.Inordernottobreakupthesupport
particlesduringthecatalystsynthesisbystirringwithamagneticstirbar,the
reagentsweregentlyshaken.Table5.4listsanoverviewofthesynthesizedcatalysts.
OnlyN5waschosenasasupportprecursor,becauseitwasthebestavailable.
ItisshowninChapter5.7,thatZiegler-Nattacatalysts,synthesizedfromCLIP
supportprecursors,havealowactivityinpropylenepolymerization,butproduce
polypropylenewithgoodstereoregularityandlowPDI.

Table5.4:CatalystspreparedfromCLIPsupports

CatalystSupportPrecursorDealcoholationInternalDonor
DIBP—N5N5N24N25N8N5SiCl4DIBP
N26N8N5SiCl4—

DealcoholationwithoutthesisSynCatalystN24wassynthesizedfromprecursorN5withoutpriordealcoholationinorderto
investigatetheinfluenceofthealcoholsduringcatalystsynthesis.Figure5.27aand
5.27bshowSEMimagesofN24.Theparticleshavelargelylostthemacroscaled
morphologicalpropertiestheyexhibitedpriortothereactionwithTiCl4.There-
actionofTiCl4andthealcohols,yieldingvarioustitaniumalkoxyspecies,leadsto

73

alossofstructuralintegrity.Yet,similartothedealcoholationwithSiCl4,TiCl4
dealcoholatesthesupportprecursorbyalkoxideformation.Thereactionismuch
strongerhowever,causingtheobservedmorphologicalissues.

(a)

(b)

Figure5.27:SEMimageofN24.

DealcoholationafterthesisSynCatalyst

N25andN26weresynthesizedfromsupportN8,whichisthedealcoholatedsup-
portprecursorN5.DIBPwasusedasaninternaldonorforN25,whereasN26
waspreparedwithoutadonor.AsevidentfromFigure5.28and5.29,theparticle
morphologyofN25andN26waspreservedduringthecatalystsynthesis,because
thealcoholsreactedwiththeSiCl4intheprecedingdealcoholation.Theassembly
ofprimaryparticleswaspreservedaswellandagglomeratedsubparticlesarevisible,
asevidentfromFigure5.28b.Nosmoothingofthesurfacehasoccurred.Theaddi-
tionofDIBPduringthesynthesisdidnothaveanimmediateeffectontheparticle
.morphology

74

(a)

(a)

Figure

Figure

5.28:

5.29:

SEM

SEM

(b)

image

(b)

image

of

of

.N25

.N26

5.7olymerizationsP

75

ThecatalystsN24,N25andN26wereusedinpropylenepolymerizationstoinves-
tigatetheirperformance.Ofgreatinterestwerethecatalysts’polymerizationac-
tivities,theirfragmentation/replicationbehavior,theirstereoregulatingeffectsand
polymerpropertiessuchasaveragemolecularmassandPDI.Anoverviewofthe
polymerizationexperimentsisgiveninTable5.5.Thepolymerizationconditions
weregearedtotheestablishedstandardconditionsasoutlinedinChapter4.3.The
Al:Si:Tiratiowasslightlyadapted.Thepolymerizationconditionsforthecatalysts
madefromCLIPsupportsarepresentedinTable5.6.

Table5.5:PolymerizationswithCLIPsupports

PolymerCatalystDealcoholationInternalDonor
DIBP—N24N27DIBPSiClN25N284SiClN26N29—4

Table5.6:SlurryPolymerizationConditionsforCLIPcatalysts

TemperatureT70
ReactorvolumeVreactor1L
Propylenepressureppropylene5.00bar
HydrogenpartialpressurepH20.36bar
SolventvolumeVsolvent350mL
Catalystamountmcatalyst15mg
PolymerizationdurationΔtpolymerization2h
Al:Si:Tiratio800:20:1
Note:Applyingtheidealgaslaw,amolarratioof6.8%hydrogeninthereactorcan
becalculated.

Themoststrikingdetailofthedataisthelowactivityofallcatalyst,ascanbe
seeninTable5.7.ComparedtoanindustrialsphericalcatalystsuchasS3,which

76

Table5.7:SummaryofthePolymerizationResultswithCLIPcatalysts

catalystpolymeractivityMnMwPDIstereoregularity
kgpolymergg[%mmmm]
gcatalyst∙hmolmol
N24N270.07800002300002.996.3
N25N280.004500003000006.091.9
N26N290.008900004000004.493.8

hasanactivityof2.44kgpolymerg−1catalysth−1inslurrypolymerizations,thetestedcat-
alystswereclosetobeingconsideredinactive.Remarkably,althoughN24wasnot
dealcoholated,itsactivitywastentimeshigherthanthatofN25andN26.

(a)

(b)Figure5.30:SEMimageofN27.

ThemoststrikingdetailoftheSEMimagestaken(Figures5.30–5.32)isthe
fact,thatthecatalystfragmentationwasnotsuccessfulandthusnofreshactive
siteswereaccessibleforthemonomer.ItcanbeseeninFigure5.31b,thatthepri-
maryparticlesbeganpolymerizing.However,duetothelowactivityofthecatalyst,
thehydraulicforceofthepolymerwasnotstrongenoughtofragmentthecatalyst.
Thecatalystssufferedfromalackofaccesstofreshactivesitesbyfragmentation,
andfromthelowperformanceofthosesitesbeingaccessibleatthebeginningofthe
polymerization.Althoughthemacroscaledmorphologyofthecatalystwaslargely
retained,apartoftheparticlesloststructuralintegrity.Thishasmorelikelyhap-

77

penedduetoanabrasionfromtheagitationduringthepolymerizationthandueto
catalystfragmentationfromgrowingpolymer.

(a)

(b)

Figure5.31:SEMimageofN28.

Thepolymerproperties,evaluatedbyGPCand13C-NMRspectroscopy,arealso
presentedinTable5.7.N27hasalowermolecularmassthanbothN28andN29.
ThePDIofN27issignificantlylowerthanthevaluesofN28andN29andthan
thevaluesfoundinliterature(seeChapter2.1).Asoutlinedbefore(Chapter2.1.2),
ahigherhomogeneityofactivesitesonthesupportleadstolowerPDIsandbetter
stereoregularity.N27alsoexhibitsthehighestdegreeofstereoregularity,indicated
bythehighestpercentageofthemmmm-pentads.Theresultsareconsistentwith
theassumptionmentionedbefore,thatpolymerswithlowPDIvaluesoftenexhibit
ahighdegreeofstereoregularity.Themostfavorablesetofproperties(relatively
highactivity,goodstereoregularityandverylowPDI)isexhibited,ifthelewisbases
(includingPEG-200)arenotremovedbymeansofdealcoholation.

78

(a)

Figure

5.32:

SEM

(b)

image

of

.N29

6Chapter

SectiontalerimenExp

RemarksGeneral6.1

6.1.1InertGasTechnique

AllmaterialmanipulationswereconductedusingSchlenktechniqueandgloveboxes
frommbrauncompany.Argon4.8wasusedasinertgasofwhichresidualwater
andimpuritieswereremovedintwocolumns,filledwithmolecularsieves(4Å)and
Süd-ChemiePolyMax301,respectively.

6.1.2Drying

Asubstancereferredtoas“dry”,hasbeendriedaccordingtothefollowingproce-
dures:n-Heptane,n-hexane,tolueneandethylbenzeneweredriedusingaluminum
oxide(neutral),degassedandstoredinthepresenceofmolecularsieves(4Å).n-
Pentanewastakenfromasolventpurificationsystem(SPS)frommbrauncompany.
Commercialpureethanolwasfurtherdriedbyrefluxinginthepresenceofmagne-
siumethoxide145andstoredinthepresenceofmolecularsieves.PEG-200,PEG-400,
PPG-425,PolyTHF-250,PDMS,DIBPandDIPSweredriedwithmolecularsieves.
Propylenewasdriedandfurtherpurifiedintwocolumnsfilledwithmolecularsieves
(4Å)andBASFBTScatalyst,respectively.

79

80

Chemicals6.1.3AllchemicalswerepurchasedfromMerck,Sigma-Aldrich,Fluka,AcrosandABCR.
PropylenewasobtainedfromBASFandLindeGas.ArgonwasobtainedfromLinde
estfalengas.WandGas

cedureProolymerizationP6.1.4Thecatalystsamplewasloadedintothesolidburetteinsideaglovebox.Prior
tothepolymerization,theinsideoftheautoclavewasdriedtoremoveresidual
water:Undertheprotectionofargon,approx.300mLn-heptanewasfilledinto
theautoclaveand6mLofa2mTEA-solutioninn-heptanewasaddedasawater
scavenger.Thesolutionwasheatedfor2hat70°C,vigorouslystirredandreleased
afterwards.Theactualpolymerizationwasconductedaccordingtothefollowing
steps:1.Fillreactorwith350mLofdryn-heptaneduringacountercurrentofargon.
Closethereactor,releaseexcesspressureandsetstirrerto400rpm.
2.Introducepropylene,untilppropylene=3bar.
3.Attachsolidburettetothereactor,whiletakingcaretoproperlyflushthe
argon.withconnections4.Add1)TEAand2)DIPStothesolidburetteundertheprotectionofargon.
Waitfor2min.
5.Pressurizesolidburettewithpargon=5barandintroducethecontentintothe
reactorbyopeningtheconnectionvalve.
6.Washthesolidburettewithdryn-pentanethreetimes,eachtimeintroducing
thecontentintothereactorbyopeningtheconnectionvalve.
7.Releasereactorpressure,untilppropylene=3bar.
8.Introducehydrogen(seebelow).
9.SetreactortemperaturetoT=70°C,setstirrerto400rpm.
10.SetppropylenetothepressureofthereactoratT=70°C.Dependingonthe
experiment,ppropylenewillbebetween5.4barand5.8bar.

11.Stopthereactionafter2h.
12.Releasethereactorcontentsthroughthebottomvalve.
13.Washanddrytheyieldedpolymer.

81

DosingHydrogen50mLofhydrogenat5bar,storedinasmallmetalcylinder,wasdosedintothe
reactoratroomtemperatureandatppropylene=3bardirectlyaftertheinjectionof
thecatalyst.Applyingtheidealgaslaw,amolarratioof6.8%hydrogeninthe
calculated.ebcanreactor

DistributionSizearticleP6.1.5AccordingtotheproceduredescribedinChapter4.6.1,thecircle-equivalentdiam-
eters(CED)ofsupport/catalystparticleswereobtainedbyanalyzingSEMimages
withImageJ,usingathresholdingalgorithm.PSDhistogramswerepreparedafter
calculatingthedistributiondensitiesq1(x)fromtheCEDvalues.

6.1.6StereoregularityDeterminationbyNMRSpectroscopy
Togatherdataaboutisolatedstereoerrors,13C{1H}-NMRspectraofpolypropylene
sampleswereobtained.ToeachNMRtube,approx.0.5mLof1,2,4-trichlorobenzene
(TCB),approx.0.1mLdimethylsulfoxide-d6(DMSO-d6,forfieldfrequencylock
andinternalstandardrelativetotetramethylsilaneat0ppm)andapprox.70mg
ofpolymerwereadded.ThespectrawererecordedatT=410K,spectrometer
frequencyf=75.47Hz,numberofscans:1024.Allspectrawerecalibratedwith
DMSO-d6,beingat40.76ppm.Ifnopentadfractionisspecified,onlythepeak
correspondingtommmmwasvisibleinthespectrum.

tEquipmen6.2

6.2.1PolymerizationAutoclave
Allpolymerizationswereconductedina1Ldouble-mantlelaboratorysteelautoclave
frombüchiglasustercompany.Theautoclavewasequippedwithamagnetically

82

coupledbladestirrer.Thefixedtopflangefeaturedseveralopeningsformanipula-
tions,suchasgascharging/venting,additionofreactants,etc.Thereactorcontents
couldbereleasedfromabottomvalvetokeeptheinsideunderinertconditions,
thuspermittingtheconductionofanotherexperimentwithoutaprecedingdrying
step.Alternatively,theautoclavecouldbeopenedbyremovingthelowerpartfrom
flange.topfixedthe

Figure6.1:1Lpolymerizationautoclave.Thesmallgascylinderforhydrogendosing
canbeseeninthetopleftcorner.

Theautoclavesetupwasequippedwithacryostat.PID-temperaturecontrolvia
athermocouple,locatedinsidethereactor,allowedfastandprecisetemperature
trol.con

SetupyMicroscopVideo6.2.2Thevideomicroscope(VM)isasetupofawindowautoclaveandareflected-light
microscope(seeFigure6.2a).Itallowsthedirectobservationofachemicalreaction
(e.g.,heterogeneouspolymerization)insidetheautoclave.Adigitalcameratakes

micrographsatselectedtimeintervals.

(a)VMsetupandturbomolecularpump
(left).

83

(b)CloseupoftheVMautoclave.Themetal
cylinderisseenunderneaththeobjective.

Figure6.2:Videomicroscopysetup.

AschematicillustrationoftheVMsetupisfoundinFigure6.3.Thevolume
oftheautoclave(1)was200mL.Aglasswindow(2),sustainingpressuresand
temperaturesupuntil20barand150°C,respectively,waslocatedbetweentheau-
toclavebodyandathreadedlid.Thelidandthewindowwasremovedtoloadthe
catalystandtheco-catalyst/externaldonormixture.Thecatalyst(3)wasplaced
ontopofasteeltable(4),locatedcloselybeneaththewindow,toreducethedis-
tanceofthemicroscope(5)tothesampleinordertoobtainfocusedmicrographs
(seeFigure6.2b).Sincethepolishedsteeltableexhibitedgroovesandscratches
atlargemagnifications,theparticleswereplacedonamicroscopycoverslip.The
slightelevationoftheparticlesbroughtthesteelsurfaceoutoffocusandleadtoa
smoothandhomogeneousbackground.Theco-catalyst/externaldonormixturewas
broughttothebottomoftheautoclave(6).Adigitalcamera(7),controlledbyan

84

externalcomputer(8),wasconnectedtothemicroscope.Thereactorwasequipped
withthreeopenings(9),tofacilitategassupply/venting,temperaturemeasurements
withathermocoupleandextramanipulations(e.g.,dosingofextrareagents;not
showninschematics).Thetemperaturewascontrolledwithathermocouple,located
insidethereactorwall(10).Thereactorwaselectricallyheatedonaheatingplate.
Acoldlightsourceprovidedproperillumination(ringlight,seeFigure6.2b).The
propylenepressurewasadaptedwithapressurecontroller.Aturbomolecularpump
wasattachedtosupplyhighvacuum(<1∙10−4mbar).

Figure6.3:SchematicillustrationoftheVMsetup.

6.2.3ScanningElectronMicroscopy,EnergyDispersiveX-
RaySpectroscopy
SEM-EDXmappingimagesweretakenbytheelectronmicroscopyinstituteatUlm
University.AllotherSEMimagesweretakenwithaHitachiTabletopMicroscope
(TM-1000).

6.2.4NuclearMagneticResonanceSpectrometer
NMRspectrawererecordedwithaBrukerARX-300spectrometer(75.47MHz).

85

6.2.5HighTemperatureGelPermeationChromatograph
HT-GPCmeasurementswereconductedwithaVarianPL-GPC220integratedGPC
system.

BuretteSolid6.2.6Thesolidburette(SB)isadevicetochargeaheterogeneouscatalystintoapres-
surizedautoclaveunderinertconditions.Itwasdevelopedtoreplacethecommonly
usedsyringetechniqueforthereasonsoutlinedinChapter4.3.4.TheSBisshown
6.4a.Figurein

(a)Solidburetteforchargingheterogeneous
catalystsintoapressurizedautoclaveun-
conditions.inertder

(b)Threepositionsofvalve2.

burette.Solid6.4:Figure

86

Pleasenotethatvalve2canbesettothreedifferentpositions(a,b,c,see
Figure6.4b).Itisdesignedtofacilitateeffectivepurgingwithargonanddosingof
conditions.inertnderuliquidsToloadacatalystsample,theSBisopenedinsideagloveboxatfitting1,making
surevalve5isclosed.Afterclosingfitting1,valve2hastobebroughtintoposition
a,thusprotectingthecatalystfromtheoutsideatmosphere.Afterconnectingvalve
5totheautoclave,argonisattachedtotheSBat4(pargon>preactor).Whenopening
valve3,theoutertubingispurgedwithargon.Afterwardsvalve2issettoposition
c.TheinsideoftheSBisnowaccessible,butstillprotectedbyargon.Asoutlined
inChapter6.1.4,TEAandDIPScannowsafelybedosedintotheSB.Valve2is
thensettopositionb.Byopeningvalve5,theslurryisinjectedintothereactor.
Theprocedurehastoberepeatedforwashingwithn-pentane.

6.3ActivationofIndustrialCatalysts

6.3.1StandardActivationProcedure
125mLoftheselectedactivationreagentwasaddedto2.5gofS3.Theslurrywas
stirredandheatedtothedesiredtemperature,whereastheliquidturnedyellow.
Afterthechosenreactiontime,theslurrywasallowedtocooldownandsettle.The
liquidwasthensiphonedoffthroughafilterandthesolidwaswashedthreetimes
withdryn-heptaneatRT.TheactivatedcatalystwasdriedapplyingSchlenkline
vacuum(≈1∙10−2mbar)overnight.

6.3.2SynthesesofActivatedCatalysts
Note:The13C-NMRdatacorrespondstopolypropylene,synthesizedwiththere-
spectivecatalyst.SeeChapter6.1.4foradetaileddescriptionofthepolymerization
cedure.pro

S3A1S3,activatedwithn-hexane
Duration:Δtactivation=90min.Temperature:Tactivation=65°C.13C-NMR(TCB/DMSO-
d6,75.47MHz)ofPP:δ21.61(mmmm),28.85,46.43;

87

S3A2S3,activatedwithn-heptane
Duration:Δtactivation=90min.Temperature:Tactivation=95°C.13C-NMR(TCB/DMSO-
d6,75.47MHz)ofPP:δ21.60(mmmm),28.84,46.41;

S3A3S3,activatedwithtoluene
Duration:Δtactivation=90min.Temperature:Tactivation=95°C.13C-NMR(TCB/DMSO-
d6,75.47MHz)ofPP:δ21.58(mmmm),28.81,46.40;

S3A4S3,activatedwithtolueneinaSoxhletextractor
Duration:Δtactivation=90min.Temperature:Tactivation=111°C.13C-NMR
(TCB/DMSO-d6,75.47MHz)ofPP:δ21.59(mmmm),28.83,46.41;

S3A5S3,activatedintoluenefor30min
Duration:Δtactivation=30min.Temperature:Tactivation=95°C.13C-NMR(TCB/DMSO-
d6,75.47MHz)ofPP:δ21.60(mmmm),28.84,46.42;

S3A6S3,activatedinethylbenzene
Duration:Δtactivation=90min.Temperature:Tactivation=95°C.13C-NMR(TCB/DMSO-
d6,75.47MHz)ofPP:δ21.64(mmmm),28.87,46.45;

S3A7S3,activatedintoluene/TiCl4,1:1
Duration:Δtactivation=90min.Temperature:Tactivation=95°C.Note:Nocolor
changewasvisible,sinceTiCl4itselfisyellow.
13C-NMR(TCB/DMSO-d6,75.47MHz)ofPP:δ21.61(mmmm),28.85,46.42;

88

S3A8S3,activatedintoluene/TiCl4,10:1
Duration:Δtactivation=90min.Temperature:Tactivation=95°C.Note:Nocolor
changewasvisible,sinceTiCl4itselfisyellow.
13C-NMR(TCB/DMSO-d6,75.47MHz)ofPP:δ21.64(mmmm),28.88,46.45;

6.3.3PolymerizationintheVideoMicroscopeAutoclave
Note:PleaserefertoChapter6.2.2forapresentationoftheVMsetup.
Priortothepolymerization,thereactorwasthoroughlycleaned,washedwithn-
pentaneandheatedto70°C.Additionally,highvacuum(<1∙10−4mbar)wasap-
pliedovernighttoensurecompletedrynessinthereactorchamber.Theentire
reactorwasthentransferredintoagloveboxforloading.Afewgrainsofcatalyst
S3wereplacedontopofthecoverslip,locatedonthesteeltable.Thesteeltable
wasthenplacedintothereactorchamber.Amixtureofco-catalyst(1.6mLofa1m
TEA-solutioninn-heptane)andexternaldonor(0.4mLofa0.2mDIPS-solutionin
n-heptane)wasinjectedintothereactorchamber.Thereactorwasclosed,takenout
ofthegloveboxandattachedtothegassupply.Afterathoroughpurgeofallcon-
nections,propylenewasslowlyintroducedintothereactoruntilppropylene=4.00bar.
Thedigitalcamerawassettotakeamicrographevery30s.Thereactorwasthen
heatedandthepressurecarefullyadjustedtoreach5.00barat70°C.Thepoly-
merizationwasstoppedafter20min(bypurgingwithargon),becausenofurther
visible.aswreaction

6.4NovelMethodfortheSynthesisofCatalystSup-
ortsp

6.4.1StandardSupportPrecursorSynthesisProcedure
First,anhydrousMgCl2wasaddedtotheopened1Lpolymerizationautoclave.It
wasthenclosedanditsatmosphereexchangedbyapplyingvacuum(≈1∙10−2mbar)
andrechargingwithargon5.0threetimes.Thethirdtime,vacuumwasappliedfor
15min.Subsequently,allreactantswereaddedtotheautoclavethroughanopening
inthetopflangeandthemanipulationswereconductedinacountercurrentof

89

argon.250mLparaffinoilwasintroducedwithaseparatoryfunnel,thestirrer
oftheautoclavewassetto400rpmandthereactorwasclosed.Theshortchain
alcohol(methanol,ethanolor1-propanol)wasaddedwhileshortlyopeningavalve
inthetopflange,andafter10mintheautoclavewasheatedto70°C.After2h,
thetemperaturewasdecreasedto25°Candthelongchainalcohol(1-octanol,1-
decanol)wasadded,againwhileshortlyopeningavalveinthetopflange.The
autoclavewasthenheatedto70°Cfor1h.Thetemperaturewasthenloweredto
25°Candthebinder(PEG-200,PEG-400,PPG-425,PDMSorPolyTHF-250)was
added,againwhileshortlyopeningavalveinthetopflange.Theautoclavewas
thenheatedto70°C.After30minthetemperaturewassetto130°Candthestirrer
setto800rpm.After30minthebottomvalvewasopenedandthecontentquickly
releasedinto≈1.2Lofdryn-pentaneat−50°Cto−40°Cina2LSchlenkflask.
ThesolidsupportprecursorwasthenfilteredoffanddriedapplyingSchlenkline
vacuum(≈1∙10−2mbar)overnight.

6.4.2SynthesesofSupportPrecursorsandCatalystSupports
N5MgCl2(5.0g,52.5mmol),ethanol(6.2mL,106.3mmol),1-decanol(4.0mL,21.0mmol),
PEG-200(1.0mL,5.6mmol).

N6Precursor(N5,2.0g),n-decane(50mL).Weightloss:13.8%.

N7Precursor(N5,2.0g).Weightloss:9.5%.

N8Precursor(N5,1.0g),SiCl4(1.5mL),n-heptane(10mL).Weightloss:15.0%.

N9Precursor(N5,3.0g),ClSi(Me)3(4.0mL),n-heptane(100mL).Weightloss:21.3%.

90

N10MgCl2(2.0g,21mmol),ethanol(2.45mL,42mmol),1-decanol(4.0mL,21mmol).

N11MgCl2(3.0g,31.5mmol),ethanol(3.68mL,63.1mmol),PEG-200(1.0mL,5.6mmol).

N12MgCl2(0.5g,5.3mmol),ethanol(0.6mL,10.3mmol),1-decanol(0.3mL,1.6mmol),
PEG-200(0.1mL,0.6mmol).

N13MgCl2(0.5g,5.3mmol),ethanol(0.6mL,10.3mmol),1-decanol(0.5mL,2.6mmol),
PEG-200(0.1mL,0.6mmol).

N14MgCl2(0.5g,5.3mmol),ethanol(0.6mL,10.3mmol),1-decanol(0.3mL,1.6mmol),
PEG-200(0.05mL,0.3mmol).

N15MgCl2(0.5g,5.3mmol),ethanol(0.6mL,10.3mmol),1-decanol(0.3mL,1.6mmol),
PEG-200(0.2mL,1.1mmol).

N16MgCl2(5.0g,52.5mmol),ethanol(6.2mL,106.3mmol),1-decanol(4.0mL,21.0mmol),
PEG-200(1.0mL,5.6mmol).

N17MgCl2(5.0g,52.5mmol),ethanol(6.2mL,106.3mmol),1-octanol(4.0mL,25.5mmol),
PEG-200(1.0mL,5.6mmol).

N18MgCl2(0.5g,5.3mmol),methanol(0.42mL,10.4mmol),1-decanol(0.99mL,5.2mmol).

91

N19MgCl2(0.5g,5.3mmol),ethanol(0.6mL,10.3mmol),1-decanol(0.6mL,3.1mmol),
PEG-400(0.1mL,0.3mmol).

N20MgCl2(5.0g,52.5mmol),ethanol(6.2mL,106.3mmol),1-decanol(4.0mL,21.0mmol),
PPG-425(2.0mL,4.7mmol).

N21MgCl2(5.0g,52.5mmol),1-propanol(7.9mL,105.0mmol),1-decanol(4.0mL,21.0mmol),
PEG-200(1.0mL,5.6mmol).

N22MgCl2(5.0g,52.5mmol),1-propanol(7.9mL,105.0mmol),1-decanol(4.0mL,21.0mmol),
PDMS(2.0mL).

N23MgCl2(5.0g,52.5mmol),1-propanol(7.9mL,105.0mmol),1-decanol(4.0mL,21.0mmol),
PolyTHF-250(4.0mL).

N24Precursor(N5,0.52g),TiCl4(10.0mL),mixture(2.0mLTiCl4,10.0mLn-decane),
DIBP(0.1mL).Yield:0.59g.

N25Support(N8,1.0g),n-heptane(10mL),TiCl4(2.0mL),mixture(4.0mLTiCl4,
15.0mLn-decane),DIBP(0.1mL).Yield:0.9g.

N26Support(N8,4.31g),n-heptane(10mL),TiCl4(4.0mL),mixture(1.0mLTiCl4,
10.0mLn-decane).Yield:0.9g.

92

olymerizationsP6.4.3Note:The13C-NMRdatacorrespondstopolypropylene,synthesizedwiththere-
spectivecatalyst.SeeChapter6.1.4foradetaileddescriptionofthepolymerization
cedure.pro

N2713C-NMR(TCB/DMSO-d6,75.47MHz)ofPP:δ20.88(mmrr,1.0%),21.42(mmmr,
2.7%),21.64(mmmm,96.3%),28.88,46.45.

N2813C-NMR(TCB/DMSO-d6,75.47MHz)ofPP:δ20.16(rrrr,1.1%),20.88(mmrr,
2.9%),21.43(mmmr,4.1%),21.66(mmmm,91.9%),28.90,46.47.

N2913C-NMR(TCB/DMSO-d6,75.47MHz)ofPP:δ20.20(rrrr,0.9%),20.90(mmrr,
2.0%),21.45(mmmr,3.3%),21.67(mmmm,93.8%),28.92,46.50.

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ofListFigures

1.1Max-Planck-InstitutfürKohlenforschunginMülheim/Ruhr......3

2.1CosseeandArlman’smechanismoftheZiegler-Nattapolymerization
ofpropylene.................................7
2.2Isotactic,syndiotacticandatacticpolypropylene............7
2.3SchematicsofthemonomercoordinationintheChargePercolation
Mechanism.................................8
2.4Ti−CbondandvacantorbitalformationduringactivationwithAlEt.14
32.5Exemplificationofthereplicationphenomenon.............15
2.6Polymergrowthaccordingtothecore-shellmodel............15
2.7Polymergrowthaccordingtothemultigrainmodel...........16
2.8Polymergrowthaccordingtothepolymerflowmodel..........17

4.1GranularcatalystG1...........................22
4.2GranularcatalystG2...........................23
4.3PSDsofG1andG2............................23
4.4SphericalcatalystS1............................24
4.5SEMimagesofsphericalcatalystS1...................25
4.6PSDofS1.................................25
4.7SEMimagesofsphericalcatalystS2...................26
4.8SphericalcatalystS2............................26
4.9SphericalcatalystS3............................27
4.10SphericalcatalystS3............................27
4.11CommercialgranularcatalystG3.....................29
4.12CommercialsphericalcatalystS4.....................30
4.13Comparisonofactivitieswithandwithoutthepresenceofhydrogen..32

103

104

4.14Weightaveragemolecularmassandpolydispersityindexagainsthy-
drogenpresence...............................34
4.15Activityagainsttitaniumconcentration.................40
4.16ComparisonofMandPDIagainsttheTitaniumConcentration...41
w134.17RepresentativeC-NMRspectrum.Displayedistherelevantmethyl
region(ca.21.6ppm–19.7ppm)ofS3A4.Onlythemmmm-pentad
atδ=21.61ppmisvisible.........................43
4.18Catalystparticles,observedatdifferentpointsoftimeduringpoly-
merization.Fiveparticleshavebeenmarked,observedandanalyzed
forpolymergrowth.............................47
4.19NormalizedCEDandSEVvalues,showingthegrowthoftheobserved
singleparticles...............................47
5.1Initialthoughtsofaformationofmacroscaledparticlesthrougha
controlledassemblyofmicroscaledsubmoieties.............50
5.2Silane-modificationofglassequipment..................52
5.3Synthesisoftheethanoladduct......................52
5.4Synthesisofthe1-decanoladduct.....................53
5.5SimplifiedillustrationofN3,beinganon-stoichiometricnetworkof
N1andN2.................................53
5.6SimplifiedillustrationofN4........................54
5.7SphericalcatalystsupportprecursorN5.................55
5.8SupportN6(precursorN5,thermallydealcoholatedundervacuum).56
5.9SupportN7(precursorN5,thermallydealcoholatedinaninertgas
stream)...................................57
5.10ReactionofN5withSiCl........................58
45.11SupportN8(precursorN5,chemicallydealcoholatedwithSiCl)...58
45.12SupportN9(precursorN5,chemicallydealcoholatedwithClSi(Me)).59
35.13SynthesisofN10..............................60
5.14SupportprecursorN10(fromthereactionofN1with1-decanol)...61
5.15SynthesisofN11..............................61
5.16SupportprecursorN11(fromthereactionofN1withPEG-200)...62
5.17Supportprecursors,madefromdifferentreactantratios.........63
5.18SEMimageofN16............................64
5.19SEMimageofN17............................65

5.205.215.225.235.245.255.265.275.285.295.305.315.32

6.16.26.36.46.5

105

SEMimageofN19............................66
Predominantspeciesofpoly(propyleneglycol)-425andpoly(ethylene
glycol)-200/400...............................67
SEMimageofN20............................67
SEMimageofN21............................68
SEMimageofN22............................69
Primarysphericalcomposites.......................70
Macroscaledfinalsphericalcomposite..................71
SEMimageofN24............................73
SEMimageofN25............................74
SEMimageofN26............................74
SEMimageofN27............................76
SEMimageofN28............................77
SEMimageofN29............................78

1Lpolymerizationautoclave.Thesmallgascylinderforhydrogen
dosingcanbeseeninthetopleftcorner.................82
Videomicroscopysetup..........................83
SchematicillustrationoftheVMsetup..................84
Solidburette................................85
InfrontofthehousewhereKarlZieglerwasborn(Helsa/Germany)..111

106

ablesTofList

4.14.24.34.44.54.64.74.84.9

5.15.25.35.45.55.65.7

ParticleSizeDistributions........................
StandardSlurryPolymerizationConditions...............
SummaryoftheCatalystActivitiesBeforeActivation.........
SummaryoftheMolecularMassAveragesandPDIsbeforeActivation
ComparisonofDosingTechniquesontheBasisofActivityBefore
Activation.................................
ActivationConditions...........................
SummaryofCatalystActivitiesAfterActivation............
SummaryoftheMolecularMassAveragesandPDIsAfterActivation
VideoMicroscopyPolymerizationConditions..............

RequirementsforaZiegler-NattaCatalystSupport..........
VariationofReactantRatios.......................
VariationofReactants..........................
CatalystspreparedfromCLIPsupports.................
PolymerizationswithCLIPsupports..................
SlurryPolymerizationConditionsforCLIPcatalysts.........
SummaryofthePolymerizationResultswithCLIPcatalysts.....

107

282931343638394244

51626572757576

108

CurriculumVitae

BornonFebruary22,1979inUlm/Germany
Married

ChristianHanisch
Rapunzelw33egUlm89077yGerman

Profession

ParticipantoftheJuniorManagersPrograminResearchand
telopmenDevRobertBoschGmbH,Stuttgart,Germany

08/2009since

University/Doctorate

01/2009–02/2005

Supervisor:Prof.Dr.Dr.h.c.BernhardRieger

01/2009–02/2007WACKER-LehrstuhlfürMakromolekulareChemie
TechnischeUniversitätMünchen/Germany

01/2007–02/2005InstitutfürAnorganischeChemieII
yUlm/GermanersitätUniv

109

ctorateDo

110

01/2005–05/2004

02/2003–10/2002

01/2005–11/1999

shipsnterIn

12/2005–11/2005

10/2003

03/2001–02/2001

08/1999–07/1999

Diploma:“Effectofanorganicfilleronthepropertiesofa
passengercartreadcompound”
RheinChemieRheinauGmbH,Mannheim/Germany
Supervisor:Prof.Dr.-Ing.OskarNuyken
Semesterabroad:CaliforniaInstituteofTechnology,
USACA,asadena,PChemicalEngineeringDepartment,Prof.MarkE.Davis
University:ChemicalEngineering(Chemie-Ingenieurwesen)
TechnischeUniversitätMünchen/Germany
Emphasis:Materialsciences

Internship:Internetresearchonthetopic“CatalysisatGer-
manandrenownedinternationaluniversities”
BayerMaterialScienceAG,Leverkusen/Germany
Internship:Introductiontometalanalytics(spectrometry,
metallography,mechanicalandchemicalmaterialstesting)
Wieland-WerkeAG,Ulm/Germany
Internship:Surfacetechnologyanddevelopment,construc-
tion,processengineering,research
BMWAG,München/Germany
Internship:Acquirementofbasicskillsinmetalprocessing
(amongothers:turning,milling,drilling,weldingandforging)
Wieland-WerkeAG,Ulm/Germany

ServiceMilitary

04/1999–07/1998

olhoSc

09/198906/1998–

08/199506/1996–

Figure6.5:

111

SecondarySchool:Humboldt-Gymnasium,Ulm/Germany
Abitur(UniversityEntranceQualification)
Schoolabroad:WyomingSeminary,CollegePreparatory
olhoScUSAA,PKingston,

Preparatory

InfrontofthehousewhereKarlZieglerwasborn(Helsa/Germany).

112