Synthesis of telechelic vinyl/allyl functional siloxane copolymers with structural control

F B Madsen,I Javakhishvili,R E Jensen,S Hvilsted,A E Daugaard,A L Skov

doi:10.1039/c4py00919c

Abstract

Multifunctional siloxane copolymers with terminal vinyl or allyl functional groups are synthesised through the borane-catalysed polycondensation of hydrosilanes and alkoxysilanes. Copolymers of varying molecular weights (w = 13 200–70 300 g mol−1), spatially well-distributed functional groups and high end-group fidelity are obtained in a facile and robust synthetic scheme involving polycondensation, end-group transformation and different functionalisation reactions such as Cu(I)-mediated azide–alkyne cycloaddition. Pendant alkyl chloride, alkyl azide, bromoisobutyryl, 4-nitrobenzene and 1-ethyl-imidazolium chloride fragments with programmable spatial distributions are incorporated in the copolymer backbones. NMR and FTIR spectroscopy as well as size exclusion chromatography corroborate the efficacy and versatility of this modular approach.

Highlights

The development of functional polymers is attracting increasing interest, due to a growing number of applications within nanotechnology, sustainability, biomedical- and energyrelated fields
The synthesis of polysiloxanes is generally accomplished through the nucleophilic substitution of chlorosilanes with water, to form low molecular weight linear silanols and cyclic siloxanes which are further reacted into high molecular weight polymers catalysed by acids or bases.[7]
Spectra were recorded in the range of 4000–650 cm−1, with 4 cm−1 resolution and 16 scans. 1H- and 13C-NMR experiments were performed on a Bruker 300 MHz spectrometer in CDCl3, while size-exclusion chromatography (SEC) was performed on a Tosoh EcoSEC HLC-8320GPC instrument equipped with RI and UV detectors and SDV Linear S columns from PSS, Mainz, Germany

Summary

Introduction

The development of functional polymers is attracting increasing interest, due to a growing number of applications within nanotechnology-, sustainability-, biomedical- and energyrelated fields. Functional polymers with specific control over architecture, polarity, functionality, solubility and reactivity are in especially high demand[1] and controlled functionalisation is often used to change bulk and/or surface properties, in order to expand the application range of a given polymer. Polysiloxanes, i.e. polymers containing Si–O–Si repeating units, are a group of polymers with significant industrial importance, since especially polysiloxane elastomers are used widely in advanced applications such as adhesives, membranes, implants and dielectric electro active polymers.[2,3,4,5,6]. Only moderate molecular weight copolymers have been achieved, and undesired silanol selfcondensation can occur and lead to disruption to a perfectly alternating copolymer structure.[9,10,11,12,13]

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Conclusion