Amphiphilic Copolymer-Based Multichannel Toolbox with Multistage Adjustable and Visualized Catalytic Properties

Multiple responsive polymers have attracted increasing attention for a wide range of applications including nanocarriers and nanocomposite catalysts. Herein, an amphiphilic block copolymer P­(NIPAAm-<i>r</i>-CA)-<i>b</i>-PMMA was synthesized by reversible addition–fragmentation chain-transfer polymerization with coumarin units embedded in the side chain. Followed by a reduction of the terminal group to hydrosulfonyl, relatively stable polymer microspheres can be prepared after self-assembling, and those microspheres could be further employed as carriers of gold nanoparticles (Au NPs) due to the strong interrelationship between −SH and Au. The polymer microspheres with Au NPs decorated onto the surface were endowed with reversible catalytic properties by adjusting temperature and UV irradiation owing to the introduction of photo-responsive coumarin units and thermo-responsive poly­(<i>N</i>-isopropyl acrylamide) segments. Moreover, the catalytic performance could be retained even after several cycles of photo- or thermo-responsive regulation. Importantly, the fluorescence of the smart polymer under different pH values was studied to clarify the mechanism of emission, laying a necessary foundation for further visualization of the catalytic process.