A Facile and Universal Strategy for Photo‐Controlled Hydrogels by Synergistic Combination of Photoacid and Acid‐Cleavable Polymer Networks

ABSTRACT Considering the advantages of precisely spatiotemporal control and noninvasive manner, the photo‐controlled hydrogels are highly desirable but their preparations still remain a significant challenge. Herein, a type of triarylsulfonium‐based photoacid generator (TSPAG) featured with high acid‐generation performance, high water‐solubility and high stability in darkness was synthesized, and then TSPAG was integrated into acid‐cleavable acylhydrazone‐crosslinked hydrogel networks to obtain photoresponsive hydrogels (TSPAG&ADH@P(DAAM‐HEA)). TSPAG could quickly generate protons and thus strong acidity under UV irradiation, which can trigger the cleavage of acylhydrazone bonds within hydrogel networks, leading to morphological change and gel–sol transition of TSPAG&ADH@P(DAAM‐HEA) hydrogels. This photo‐controlled disintegration and degradation behaviors can endow TSPAG&ADH@P(DAAM‐HEA) hydrogels with desirable ability for various applications. Furthermore, we demonstrated the concept of TSPAG&ADH@P(DAAM‐HEA) hydrogels as photo‐controlled actuators and photoetching patterns. This study indicated the synergistic integration of photoacid and acid‐cleavable hydrogel networks can provide a facile and promising strategy to endow acid‐sensitive hydrogel with desirable photoresponsiveness. Considering the easily available agents, simple preparation process and multifarious acid‐sensitive groups as well as precisely spatiotemporal control of photo, the strategy designed herein can expand the substrate range of photoresponsive polymer materials for multifarious applications and develop photosensitive materials without the limitations associated with conventional photosensitive reagents.