Thermal and pH Dual Responsive Copolymer and Silver Nanoparticle Composite for Catalytic Application

N-Isopropylacrylamide and vinyl imidazole copolymer,P(NIPAM-co-VI),was synthesized by free radical emulsion polymerization.Then,the copolymer and silver nanoparticle composite,P(NIPAM-co-VI)-Ag,was pre-pared by in situ reduction of AgNO3 with NaBH4.Due to the coexistence of thermal-responsive PNIPAM and pH-responsive PVI,P(NIPAM-co-VI)and P(NIPAM-co-VI)-Ag exhibited both thermal and pH responsibility,their size would change while altering the temperature or pH of the circumvent.Their thermal and pH dual responsive properties were studied by dynamic light scattering(DLS).P(NIPAM-co-VI)-Ag could be stably dispersed in water at a pH range from 3.0 to 9.3,which is favorable to use P(NIPAM-co-VI)-Ag as a catalyst in the reduction reaction of p-nitrophenol.The reaction rate constant(kapp)increased with the decrease of pH or the increase of VI content in the copolymer.