Synthesis and self-assembly of multiple thermoresponsive amphiphilic block copolymers [Elektronische Ressource] / Jan Weiß. Betreuer: André Laschewsky

Jan Weiß

Informations

• Publié par: universitat_potsdam
• Publié le: 01 janvier 2011
• Nombre de lectures: 55
• Langue: Deutsch
• Poids de l'ouvrage: 15 Mo

Extrait

Synthesis and Self-Assembly of Multiple
Thermoresponsive Amphiphilic Block Copolymers
A dissertation submitted to
University of Potsdam
Department of Chemistry
for the degree of
“doctor rerum naturalium”
(Dr. rer. nat.)
in Macromolecular Chemistry
Presented by
Jan Weiß
Supervisor Prof. A. Laschewsky
Potsdam 2011











































Published online at the
Institutional Repository of the University of Potsdam:
URL http://opus.kobv.de/ubp/volltexte/2011/5336/
URN urn:nbn:de:kobv:517-opus-53360
http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-53360 Danksagung
Mein Dank geht an Prof. Dr. A. Laschewsky für die Möglichkeit meine Dok-
torarbeit in seiner Gruppe anfertigen zu können und für die Unterstützung
und Diskussionen während dieser Zeit. Ferner möchte ich Dr. J. van Heijst
und Dr. H. Rüegger, der das Ende dieser Arbeit aufgrund tragischer Um-
stände leider nicht mehr miterleben kann, für die Möglichkeit danken, tem-
peraturabhängige NMR Spektren an der ETH Zürich messen zu können,
Dr. C. Böttcher für die TEM Messungen, Prof. Dr. S. Beuermann und Herrn
S. Prentzel für SEC Messungen, Dr. N. Hildebrandt und Dr. S. Stufler für
den Zugang zum Fluoreszenzspektrometer sowie Prof. Dr. J. Beckmann und
Prof. Dr. H. Frauenrath für hilfreiche Diskussionen.
Ausserdem möchte ich Dr. Achille Bivigou-Koumba für die zahlreichen
Diskussionen und die praktischen Ratschläge, besonders in der An-
fangsphase meiner Promotionszeit und Maike Lukowiak für den Zugang zu
einiger Literatur danken.
Des Weiteren möchte ich Dr. Nezha Badi für die hilfreichen Diskussionen,
Korrekturen dieser Arbeit, die Unterstützung sowie für die wundervolle Zeit
auch neben der Arbeit, die meine drei Jahre in Potsdam unvergesslich macht,
von ganzem Herzen danken.
Zu guter Letzt geht noch ein besonderer Dank an meine Familie, insbeson-
dere an meine Mutter für ihre fortwährende Unterstützung in jeglicher Hin-
sicht.ListofPublications
Parts of this Ph.D. thesis were published in scientific journals and were presented in oral
presentations as well as on posters at several occasions by the author of this thesis.
Publications(peer-reviewed)
1[1] “Universal Polymer Analysis by H NMR Using Complementary Trimethylsilyl End
Groups”, M. Päch, D. Zehm, M. Lange, I. Dambowsky, J. Weiss, A. Laschewsky, J. Am.
Chem. Soc., 2010, 132, 8757-8765.
[2] “Self-Assembly of Double Thermoresponsive Block Copolymers End-capped with
Complementary Trimethylsilyl Groups”, J. Weiss, C. Böttcher, A. Laschewsky, Soft Mat-
ter, 2011, 7, 483-492.
[3] “Temperature Induced Self-Assembly of Triple Thermoresponsive Triblock Copoly-
mers in Aqueous Solution”, J. Weiss, A. Laschewsky,Langmuir, 2011, 27, 4465-4473.
[4] “Ferrocenyl (Meth)Acrylates in RAFT Polymerization”, C. Herfurth, D. Voll, J. Buller,
J. Weiss, C. Barner-Kowollik, A. Laschewsky, submitted to J. Polym. Sci. Part A: Polym.
Chem.
Publications(tobesubmitted)
[5] “Water-soluble Random and Alternating Copolymers of Styrene Monomers with
Adjustable Lower Critical Solution Temperature”, J. Weiss, A. Li, E. Wischerhoff,
A. Laschewsky*, to be submitted.
[6] “Facile One-Step Synthesis of Double Thermosensitive Diblock Copolymers”, J. Weiss,
A. Laschewsky*, to be submitted.
IVOral Presentations
[1] “A Trimethylsilyl-labeled RAFT-Agent as NMR Probe for Reversible Block Copolymer
rdSelf-Assembly”, 13.07.2010, 43 IUPAC World Polymer Congress, Glasgow, UK.
[2] “Multistep Self-Assembly of Thermoresponsive Block Copolymer Surfactants”,
th03.05.2011, 45 International Detergency Conference (IDC), Düsseldorf, Germany.
PosterContributions
[1] “Temperature Induced Self-Assembly of Triple-Responsive Triblock Copolymers in
Aqueous Solutions”, PhD Student’s Workshop Functional Soft Matter, Potsdam, Ger-
many, 2010.
[2] “Temperature Induced Self-Assembly of Triple-Responsive Triblock Copolymers in Di-
rdlute Aqueous Solution”, 43 IUPAC World Polymer Congress, Glasgow, UK, 2010.
[3] “Self-Assembly of Triple-Thermoresponsive Triblock Copolymers in Dilute Aqueous
Solution”, Polymers in Biomedicine and Electronics - Biannual Meeting of the GDCh-
Division Macromolecular Chemistry and Polydays 2010, Berlin, Germany, 2010.
[4] “Improving the IQ of Intelligent Block Copolymer Surfactants: Designs for Multiple
thSwitching”, 6 European Detergency Conference, Fulda, Germany, 2010.
[5] “Sequential Self-Assembly of Multiple Thermoresponsive Block Copolymers”, Makro-
molekulares Kolloquium, Freiburg, Germany, 2011.
VSummary
In the present thesis, the self-assembly of multi thermoresponsive block copolymers in di-
lute aqueous solution was investigated by a combination of turbidimetry, dynamic light
scattering, TEM measurements, NMR as well as fluorescence spectroscopy. The succes-
sive conversion of such block copolymers from a hydrophilic into a hydrophobic state in-
cludes intermediate amphiphilic states with a variable hydrophilic-to-lipophilic balance.
As a result, the self-organization is not following an all-or-none principle but a multistep
aggregation in dilute solution was observed. The synthesis of double thermoresponsive di-
block copolymers as well as triple thermoresponsive triblock copolymers was realized us-
ing twofold-TMS labeled RAFT agents which provide direct information about the average
1molar mass as well as residual end group functionality from a routine H NMR spectrum.
First a set of double thermosensitive diblock copolymers poly(N-n-propylacrylamide)-b-
poly(N-ethylacrylamide) was synthesized which differed only in the relative size of the two
blocks. Depending on the relative block lengths, different aggregation pathways were found.
Furthermore, the complementary TMS-labeled end groups served as NMR-probes for the
self-assembly of these diblock copolymers in dilute solution. Reversible, temperature sensi-
tive peak splitting of the TMS-signals in NMR spectroscopy was indicative for the formation
of mixed star-/flower-like micelles in some cases.
T T1 2
n m
Moreover, triple thermoresponsive triblock copolymers from poly(N-n-
propylacrylamide) (A), poly(methoxydiethylene glycol acrylate) (B) and poly(N-
ethylacrylamide) (C) were obtained from sequential RAFT polymerization in all possible
block sequences (ABC, BAC, ACB). Their self-organization behavior in dilute aqueous
solution was found to be rather complex and dependent on the positioning of the different
blocks within the terpolymers. Especially the localization of the low-LCST block (A) had a
large influence on the aggregation behavior. Above the first cloud point, aggregates were
VIonly observed when the A block was located at one terminus. Once placed in the middle,
unimolecular micelles were observed which showed aggregation only above the second
phase transition temperature of the B block. Carrier abilities of such triple thermosensitive
triblock copolymers tested in fluorescence spectroscopy, using the solvatochromic dye Nile
Red, suggested that the hydrophobic probe is less efficiently incorporated by the polymer
with the BAC sequence as compared to ABC or ACB polymers above the first phase transition
temperature.
In addition, due to the problem of increasing loss of end group functionality during the
subsequent polymerization steps, a novel concept for the one-step synthesis of multi
thermoresponsive block copolymers was developed. This allowed to synthesize double
thermor di- and triblock copolymers in a single polymerization step. The copoly-
merization of different N-substituted maleimides with a thermosensitive styrene derivative
(4-vinylbenzyl methoxytetrakis(oxyethylene) ether) led to alternating copolymers with vari-
able LCST. Consequently, an excess of this styrene-based monomer allowed the synthesis of
double thermoresponsive tapered block copolymers in a single polymerization step.
R
N OO
RAFT or ATRP
alternating block homopolymer
t0
O
O
4
Furthermore, by using bifunctional initiators, even double thermosensitive binary tri-
block copolymers could be synthesized. Both types of polymers showed an aggregation be-
havior similar to the one of block copolymers obtained by the classical step-wise approach
indicating the successful one-step synthesis of multi responsive block copolymers.
VIIZusammenfassung
Im Rahmen der vorliegenden Arbeit wurde die Selbstorganisation von mehrfach ther-
misch schaltbaren Blockcopolymeren in verdünnter wässriger Lösung mittels Trübungspho-
tometer, dynamischer Lichtstreuung, TEM Messungen, NMR sowie Fluoreszenzspek-
troskopie untersucht. Die schrittweise Überführung eines hydrophilen in ein hydrophobes
Blockcopolymer beinhaltet ein oder mehr amphiphile Zwischenstufen mit einstellbarem
hydrophilen zu lipophilen Anteil (HLB). Dies führt dazu, dass die Selbstorganisation
solcher Polymere in Lösung nicht nur einem Alles-oder-nichts-Prinzip folgt sondern ein
mehrstufiges Aggr