Electrochemically Mediated Reversible Addition–Fragmentation Chain-Transfer Polymerization

Abstract

An electrochemically mediated reversible addition-fragmentation chain-transfer polymerization (<i>e</i>RAFT) of (meth)acrylates was successfully carried out via electroreduction of either benzoyl peroxide (BPO) or 4-bromobenzenediazonium tetrafluoroborate (BrPhN₂⁺) which formed aryl radicals, acting as initiators for RAFT polymerization. Direct electroreduction of chain transfer agents was unsuccessful since it resulted in the formation of carbanions by a two-electron transfer process. Reduction of BrPhN₂⁺ under a fixed potential showed acceptable control, but limited conversion due to the generation of a passivating organic layer grafted on the working electrode surface. However, using fixed current conditions, easier to implement than fixed potential conditions, conversions > 80% were achieved. Well-defined homopolymers and block copolymers with a broad range of targeted degrees of polymerization were prepared.