Dual Switching in Both RAFT and ROP for Generation of Asymmetric A2A1B1B2 Type Tetrablock Quaterpolymers

Abstract

In reversible addition–fragmentation chain transfer (RAFT) polymerization, monomers are divided into “more-activated” monomers (type-A1 monomer) and “less-activated” monomers (type-A2 monomer). In ring-opening polymerization (ROP), monomers are considered to fall into electrophilically polymerizable monomers (lactones and carbonates, type-B1 monomer) and nucleophilically polymerizable monomers (lactides and carbonates, type-B2 monomer). Developing a strategy to copolymerize the four kinds of monomers for formation of asymmetric A2A1B1B2 type tetrablock quaterpolymers by one-pot sequential ROP and RAFT polymerization is a challenge. Herein, we designed and synthesized a molecule, 2-hydroxyethyl 2-(methyl(pyridin-4-yl)carbamothioylthio)propanoate, which functioned as a trifunctional initiator, to initiate ROPs and to modulate RAFT polymerizations sequentially in one-pot. We proposed a dual “acid/base switch” strategy in both RAFT polymerizations and ROPs for one-pot generation of asymmetric A2A1B1B2 type te...