A thermosensitive hydrogel carrier for nickel nanoparticles

Segments of a p(NIPA-co-AMPS) hydrogel synthesized from N-isopropyl acrylamide (NIPA) and 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) with N,. N'-methylenebis(acrylamide) (BIS) acting as cross-linker stabilized nickel nanoparticles (Ni-NPs) of uniform size in an aqueous solution. The rate of catalysis of the borohydride reduction of 4-nitrophenol to 4-aminophenol by these nanoparticles shows a complex temperature variation consistent with the hydrogel changing from a contracted to an expanded state below a lower critical solution temperature, LCST, of ~. 310. K. These observations provide insights into nanoparticle stabilization and catalysis and indicate potential pathways toward stable sophisticated nanoparticle catalysts for use in aqueous solution.