Novel synthesis of block copolymers via the RAFT process
Date
2007-12
Authors
Bowes, Angela
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The synthesis of complex architectures, namely block copolymers with tailored enduse
properties, is currently an important research area in academia and industry. The
challenge is finding a versatile polymerization technique capable of controlling the
molecular properties of the formed copolymers, which in turn determines their
macroscopic properties. Reversible addition-fragmentation chain transfer (RAFT)-
mediated living polymerization is a robust technique capable of producing controlled
polymer products. With the great advances in living polymerization techniques and
the environmental awareness of society there is an increasing demand to produce
these polymer products via the RAFT living technique in heterogeneous media.
Conventional emulsion and miniemulsion polymerization present various problems
when used to produce polymers mediated by the RAFT process. There is an inherent
need to find cost effective and flexible operating conditions to conduct RAFT
polymerization in heterogeneous media with the ability to produce well-defined block
copolymers.
In this study the use of three novel trithiocarbonate RAFT agents to produce welldefined
AB-type, ABA-type and star block copolymers via the RAFT process was
investigated. Optimal operating conditions for the production of living block
copolymers in homogenous and heterogeneous media were determined. The main
focus was on the development of the RAFT process in heterogeneous media to
efficiently produce block copolymer latex products. The RAFT-mediated
miniemulsion polymerization system stabilized with non-ionic surfactants was
thoroughly investigated. The ability of the ab initio and in situ RAFT-mediated
emulsion polymerization systems to produce controlled latexes was demonstrated.
Controlled block copolymer products were successfully synthesized in homogenous
and heterogeneous media via the RAFT process when the optimum reaction
conditions were chosen.
Description
Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2007.
Keywords
RAFT polymerization, Block copolymers, Addition polymerization, Emulsion, Dissertations -- Polymer science, Theses -- Polymer science