Light‐Responsive Block Copolymer Nanosheets With Well‐Ordered and Switchable Channels

ABSTRACT Light‐responsive shape‐switching block copolymer (BCP) particles have garnered growing interest in recent years. Although significant efforts have been devoted to controlling the light‐triggered morphological transformation of BCP particles, precisely modulating their morphologies using visible light remains a formidable challenge. Herein, we fabricated the light‐responsive polystyrene‐ b ‐poly(4‐vinylpyridine) (PS‐ b ‐P4VP) nanosheets via emulsion‐confined assembly in a spiropyran photoacid (SPPA) solution. Upon exposure to visible light, the non‐porous nanosheets gradually transformed into porous nanosheets with hexagonally arrayed P4VP cylindrical pores, attributed to proton release from SPPA photoisomerization under irradiation and subsequent pH‐dependent switching of P4VP cylindrical channels. Besides, owing to the reversibility of SPPA photoisomerization, the resulting porous nanosheets can revert to the non‐porous nanosheets in the dark. Furthermore, nanosheets with a controlled pore structure can serve as templates for the in situ deposition of gold nanoparticles (AuNPs), yielding hybrid PS‐ b ‐P4VP/AuNPs nanosheets with tunable porosity. The hybrid nanosheets can be used as catalysts for the reduction of 4‐nitrophenol, and the porous nanosheets exhibited greater catalytic efficiency than the non‐porous nanosheets. Thus, the reversible morphological transition of BCP particles can be precisely modulated by visible‐light stimulus and BCP particles can function as scaffolds for constructing hybrid BCP/NPs particles with adjustable catalytic efficiency, thereby broadening their application.