Synthesis of Discrete Oligomers by Sequential PET‐RAFT Single‐Unit Monomer Insertion

• Published in: Angewandte Chemie International Edition Vol. 56; no. 29; pp. 8376 - 8383
• Main Authors: Xu, Jiangtao, Fu, Changkui, Shanmugam, Sivaprakash, Hawker, Craig J., Moad, Graeme, Boyer, Cyrille
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 10.07.2017; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Activation energy; Amino acid sequence; Chains (polymeric); Chemical synthesis; Chemistry; Chemistry, Multidisciplinary; Construction; Copolymers; Dimers; Energy consumption; Energy transfer; Fragmentation; Graft copolymers; Hexamers; Insertion; Materials selection; Oligomers; photopolymerization; Physical Sciences; Polyethylene terephthalate; Polymers; RAFT polymerization; Reagents; Science & Technology; Selectivity; sequence control; single unit monomer insertion; Trimers; sequence control; photopolymerization; ACRYLATE OLIGOMERS; POLYMERS; ITERATIVE EXPONENTIAL-GROWTH; MULTIBLOCK COPOLYMERS; STEP; RAFT polymerization; CHAIN; REGULATED VINYL COPOLYMERS; MEDIATED POLYMERIZATION; N-PHENYLMALEIMIDE; single unit monomer insertion; RADICAL POLYMERIZATIONS
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201610223

Uniform synthetic polymers with precisely defined molar mass and monomer sequence (primary structure) have many potential high‐value applications. However, a robust and versatile synthetic strategy for these materials remains one of the great challenges in polymer synthesis. Herein we describe proof‐of‐principle experiments for a modular strategy to produce discrete oligomers by a visible‐light‐mediated radical chain process. We utilize the high selectivity provided by photo‐induced electron/energy transfer (PET) activation to develop efficient single unit monomer insertion (SUMI) into reversible addition–fragmentation chain‐transfer (RAFT) agents. A variety of discrete oligomers (single unit species, dimers, and, for the first time, trimers) have been synthesized by sequential SUMI in very high yield under mild reaction conditions. The trimers were used as building blocks for the construction of uniform hexamers and graft copolymers with precisely defined branches. One by one: A modular strategy produces uniform oligomers via a visible light‐mediated radical‐chain process in the presence of photoredox catalysts and RAFT agents. A variety of short oligomers (trimers) have been successfully synthesized by sequential monomer addition with high yield under mild reaction conditions.