Synthesis of novel random and block copolymers of tert-butyldimethylsilyl methacrylate and methyl methacrylate by RAFT polymerization

Abstract

Hydrophobic-hydrolysable copolymers consisting of methyl methacrylate (MMA) and tert-butyldimethylsilyl methacrylate (TBDMSMA) have been synthesized for the first time by Reversible Addition–Fragmentation chain Transfer (RAFT) polymerization technique using cumyl dithiobenzoate (CDB) and cyanoisopropyl dithiobenzoate (CPDB) as chain transfer agents (CTAs). The monomer reactivity ratios for TBDMSMA (r1=1.40±0.03) and MMA (r2=1.08±0.03) have been determined using a non-linear least-squares fitting method. Well-defined random copolymers PMMA-co-PTBDMSMA have been prepared. Then, the versatility of the RAFT process to synthesize silylated block copolymers with controlled molecular weights and low polydispersities has been demonstrated using two strategies: the synthesis of PMMA–SC(S)Ph or PTBDMSMA–SC(S)Ph as macro-chain transfer agent (macro-CTA) for use in a two step method or an one-pot method which consists in the successive addition of the two monomers. Diblock copolymers with narrow molecular weight distributions (PDI<1.2) were obtained from the one-pot method with number-average molecular weight values within the range 10,000–22,000gmol−1.