From amphiphilic block copolymers to ferrocenyl-functionalized polymers for biosensoric applications [Elektronische Ressource] / Francisco Javier López Villanueva

Storm Jameson

Informations

• Publié par: johannes_gutenberg-universitat_mainz
• Publié le: 01 janvier 2007
• Nombre de lectures: 16
• Langue: English
• Poids de l'ouvrage: 9 Mo

Extrait

“ FROM AMPHIPHILIC BLOCK COPOLYMERS
TO FERROCENYL-FUNCTIONALIZED POLYMERS
FOR BIOSENSORIC APPLICATIONS ”





Dissertation
zur
Erlangung des Grades

„ Doktor der Naturwissenschaften ”

am Fachbereich Chemie, Pharmazie und Geowissenschaften
der Johannes Gutenberg – Universität in Mainz







Francisco Javier López Villanueva


geboren in Rüsselsheim (Deutschland)


Mainz 2007


































Ein guter Ingenieur ist immer
ein bisschen konservativ …
zumindest auf dem Papier.

Scotty (in StarTrek – TNG)

ABSTRACT
The present thesis can be divided in three main parts. In all parts new polymer archi-
tectures were synthesized and characterized concerning their special features.
The first part will emphasize the advantage of a polystyrene-block-(hyperbranched
polyglycerol) copolymer in comparison to an analogue polystyrene-block-(linear poly-
glycerol) copolymer. Therefore a synthethic route to prepare linear block copolymers
has been developed. Two strategies were examined. One strategy was based on the
classic, sequential anionic polymerization; the second strategy was based on a
“Click-Chemistry” coupling reaction. In a following step glycidol was hypergrafted
from these block copolymers by applying a hypergrafting reaction with glycidol. The
behavior of the amphiphilic block copolymers synthesized was studied in different
solvents. Furthermore the polarity of the solvent was changed to form the corre-
sponding inverse micelles. DLS, SLS, SEC-MALLS-VISCO, AFM and Cyro TEM
measurements were performed to obtain a visual image from the appearance of the
aggregates. It was found that a linear-hyperbranched architecture is necessary, if
well defined, monodisperse aggregates are required, e.g. for the preparation of or-
dered nanoarrays. Linear-linear block copolymers formed only polydisperse aggre-
gates. Additionally it was found that size distribution could be improved dramatically
by passing the aggregates through a SEC column with large pores. The SEC col-
umns acted like a template in which the aggregates adopt a more stable conforma-
tion.
In the second part anionic polymerization was employed to synthesize silane-
endfunctionalized macromonomers with different molecular weights based on polybu-
tadiene and polyisoprene. These were polymerized by a hydrosilylation reaction in
bulk to obtain branched polymers, using Karstedt’s catalyst. Surprisingly the addition
of monofunctional silanes during the polymerization had only a minimal effect con-
cerning the degree of polymerization. It was possible to introduce silanes without in-
creasing the overall number of reaction steps by a very convenient “pseudo-copoly-
merization” method. All branched polymers were analyzed by SEC, SEC-MALLS,
1SEC-viscometry, H-NMR-spectroscopy and DSC concerning their branching ratio.
The branching parameters for the branched polymers exhibited similar characteristics
as hyperbranched polymers based on AB monomers. Detailed kinetic study showed 2
that the polymerization occurred very rapidly in comparison to the hydrosilylation po-
lymerization of classical AB type carbosilanes monomers. 2
The last part will deal with ferrocenyl-functionalized polymers. On the one hand,
ferrocenyl-functionalized polyglycerols (PG) were studied. Esterification of PGs with
different molecular weight using ferrocenemonocarboxylic acid gave the ferrocenyl
funtionalized polymers in high yields. On the other hand three different block copoly-
mers were prepared with different ratios of styrene to butadiene units (10:1, 4:1, 2:1).
The double bonds of the 1,2-PB block were hydrosilylated using silanes bearing one
(HSiMe Fc) or two (HSiMeFc ) ferrocene units. High degrees of functionalization 2 2
were obtained (up to 83 %). In this manner, six different ferrocenyl-rich block co-
polymers with different fractions of ferrocene were prepared and analyzed, employing
NMR-spectroscopy, SEC, SEC/MALLS/viscometry, DLS and cyclic voltammetry. The
redox properties of the studied polymers varied primarily with the nature of the silane
unit attached. Additionally, the redox properties in solution of the studied polymers
were influenced by the block length ratio of the block copolymers. Unexpectedly, with
increasing block length of the ferrocenyl block the fraction of active ferrocenes de-
creased. Nevertheless, in case of thin monolayer films this behaviour was not ob-
served. All polymers (PG and PS-b-PB based) exhibited good electrochemical prop-
erties in a wide range of solvents, which rendered them very interesting for biosen-
soric applications. TABLE OF CONTENTS

1. Introduction ............................................................................................................................ 7
1.1. Hyperbranched Polymers ................................................................................................ 7
1.1.1. Natural Origins......................................................................................................... 7
1.1.2. Mankind’s Answer ................................................................................................... 8
1.1.3. Degree of Branching .............................................................................................. 10
1.1.4. Contraction Factors 12
1.2. Synthetic Concepts........................................................................................................ 13
1.2.1. Inimer Concept....................................................................................................... 13
1.2.2. Slow Monomer Addition........................................................................................ 14
1.3. Block Copolymers 17
1.3.1. Structural Considerations ....................................................................................... 17
1.3.2. Linear-Dendritic Block Copolymers...................................................................... 19
1.3.3. Linear-Hyperbranched Block Copolymers ............................................................ 20
2. Objectives............................................................................................................................. 23
2.1. Introduction ................................................................................................................... 23
2.2. Particular Objectives ..................................................................................................... 25
2.2.1. Amphiphilic Block Copolymers – Synthesis ......................................................... 25
2.2.2. Amymers – Aggregation..................................................... 25
2.2.3. Branched Polydienes.............................................................................................. 26
2.2.4. Ferrocenyl Functionalized Polyglycerols............................................................... 27
2.2.5. Ferrocenyl Functionalized PS-block-PB Copolymers............................................ 27
3. Amphiphilic Block Copolymers – Synthesis ....................................................................... 29
3.1. Introduction..... 29
3.1.1. “Click-Chemistry”.................................................................................................. 29
3.2. Synthesis of Linear Block Copolymers......................................................................... 31
3.2.1. By Sequential Anionic Polymerization.................................................................. 31
3.2.2. “Click”-Coupling to AB-type Copolymers ............................................................ 35
3.2.3. “Click”-Coupling to ABA-type Copolymers ......................................................... 39
3.3. Hypergrafting of the linear block copolymers .............................................................. 41
3.4. Conclusion..................................................................................................................... 43
3.5. Experimental Part.......................................................................................................... 44
3.5.1. Materials................................................................................................................. 44
3.5.2. Synthesis of Styrene Homopolymers ..................................................................... 45
3.5.3. Synthesis of PEEGE Homopolymers 47
3.5.4. Synthesis of Block Copolymers ............................................................................. 48
4. Amphiphilic Block Copolymers – Aggregation................................................................... 50
4.1. Introduction ................................................................................................................... 50
4.1.1. Principles of Light Scattering................................................................................. 50
4.1.2. SEC with Triple Detection ..................................................................................... 54
4.2. Dynamic and Static Light