Tailoring Polymerization Controllability and Dispersity through a Photoswitchable Catalyst Strategy.

Modulating on-demand polymerization is a challenge in synthetic macromolecules. Herein, tailoring polymerization controllability and dispersity during single-electron transfer mediated living radical polymerization (SET-LRP) of MMA was achieved. Hexaarylbiimidazole (HABI) was employed as a photoswitchable catalyst, allowing reversible control of catalytic activity between an active and inactive state. In the presence of HABI and with light on (active state), controlled SET-LRP of MMA followed first-order kinetics, resulting in polymers with narrow molecular weight distribution. In contrast, polymerization responded to light and reverted to their original uncontrolled state with light off (inactive state). Therefore, repeatable resetting polymerization could be easily performed. The key to photomodulating dispersity is to use an efficient molecular switch to tailor the breadths of dispersity. Besides, the mechanism of HABI-mediated SET-LRP with switchable ability is proposed. This article is protected by copyright. All rights reserved.