RAFT Polymerization of Vinylthiophene Derivatives and Synthesis of Block Copolymers Having Cross-Linkable Segments

Abstract

The polymerization of three vinylthiophene derivatives, 2-vinylthiophene (2VT), 3-vinylthiophene (3VT), and 2,5-dibromo-3-vinylthiophene (DB3VT), was carried out by reversible addition−fragmentation chain transfer (RAFT) process using six different chain transfer agents (CTAs). The novel doubly polymerizable monomer, DB3VT, undergoes controlled radical polymerization via the RAFT process, followed by Suzuki coupling reaction. Two dithiobenzoate-type RAFT agents, phenylethyl dithiobenzoate (CTA 2) and cumyl dithiobenzoate (CTA 3), were the most efficient to obtain poly(DB3VT) with controlled molecular weights and low polydispersities (Mw/Mn = 1.05−1.15). Good control of the polymerization of DB3VT was confirmed by the linear increase in the molecular weight with the conversion and the ability to extend the chain by a second addition of the monomer. Chain extension from poly(methyl methacrylate) to DB3VT could be well controlled under suitable conditions and provided block copolymers having cross-linkable p...