Leveraging reactivity to gain precise control over macromolecular structures with photocatalysis in reversible-deactivation radical polymerizations

Abstract

Photocatalysis has gained a prominent role in reversible-deactivation radical polymerization (RDRP) techniques. Photocatalyzed polymerizations are appealing due to ease of implementation, oxygen tolerance, spatiotemporal and orthogonal control, and increased uniformity in polymer chain ends compared to exogenous initiation. Due to these attractive features, photocatalysis has been widely used and incorporated into atom transfer radical polymerization (ATRP) and reversible addition–fragmentation chain transfer (RAFT) polymerization. Herein, recent examples of photocatalysis in RDRP techniques at the macroscopic, topological, and primary sequence levels of control are presented to highlight how photocatalysis has led to advances at all levels of polymer chemistry. For example, photocatalysis can be used for the selective photoactivation of distinct end-groups, enabling the synthesis of sequence-defined oligomers/polymers, or complex polymer topologies. However, there are still significant gaps in photocatalyzed RDRP (e.g., kinetic understanding of photocatalyst (PC) interplay with different chain ends, PC development, and effects of reaction conditions on PC performance). By identifying how photocatalysis and reaction conditions can be tuned to mediate polymerization kinetics and selectivity, more defined and controlled polymer sequences, topologies, and macroscopic properties will be unlocked.