Ultrathin Polymersomes with Controllable Light‐Responsivity via Adjusting the Electronic Effect from <i>Para</i> ‐Substituents of Azobenzene

Achieving ultrathin polymersomes (UTPSs) with controllable light-responsive kinetics poses a prospective strategy to address the growing demands of intelligent and miniature systems, but it remains challenging. Herein, we reported the self-assembly of numerous side-chain-type amphiphilic alternating azocopolymers (AAACs) into a series of UTPSs with diameters spanning 210-270 nm and ultrathin vesicular thickness spanning 1.91-2.14 nm. The light-triggered reversible size transitions for these UTPSs are rendered by the photo-isomerization of azobenzene moiety upon alternating irradiation with UV and visible light. The systematical isomerization kinetic study proved that the light-responsive rate of distinct UTPSs was highly dependent on the electronic effect of para-substituents of azobenzenes within AAACs. Notably, the rate constant of electron-withdrawing nitro-modified UTPSs was 6.7 times greater than that of electron-donating hydroxyl-modified UTPSs. The proof-of-concept cargo release activity for different UTPSs was evaluated using a hydrophilic model drug of methylene blue (MB), with a light-controllable releasing performance that highly depended on the para-substituent-induced light-responsive kinetics. Our work offers an innovative strategy to fabricate stimuli-responsive UTPSs with a controllable responsive performance for the targeted applications in bionanotechnology.