Sequence-Controlled Methacrylic Multiblock Copolymers: Expanding the Scope of Sulfur-Free RAFT

Sulfur-free reversible addition–fragmentation transfer polymerization (SF-RAFT) in emulsion allows access to the synthesis of sequence-controlled methacrylic multiblock copolymers. Herein, we expand the scope of SF-RAFT emulsion polymerization by utilizing four different macrochain transfer agents (mCTA) to mediate the synthesis of diblocks and sequence-controlled methacrylic multiblock copolymers. Poly­(methyl methacrylate) (pMMA), poly­(butyl methacrylate) (pBMA), poly­(ethyl methacrylate) (pEMA), and poly­(benzyl methacrylate) (pBzMA) of a similar <i>M</i>_n (∼4300 g mol^–1) were successfully synthesized via catalytic chain transfer polymerization (CCTP) in emulsion. The capability of these mCTAs to act as macroinitiators was investigated through the synthesis of “<i>in situ</i>” diblock copolymers and was then expanded to the synthesis of deca- and hexablock multiblock copolymers with varying degrees of polymerization (DP_n = 10–50 per block, <i>M</i>_n,total = 7000–55 000 g mol^–1), yielding well-defined copolymers with controlled molecular weights, quantitative conversions (>99%), and low dispersities (<i>Đ</i> ∼ 1.2) without employing sulfur or transition metal reagents