Highly catalytic activity of nickel nanoparticles generated in poly(methylmethacrylate)@poly(2-hydroxyethylmethacrylate) (PMMA@PHEMA) core-shell micelles for the reduction of 4-nitrophenol (4-NP)

Excellent catalytic reduction of 4-NP in aqueous solution was achieved under ambient condition using nickel (Ni) nanoparticles generated in PMMA@PHEMA polymeric micelles. Ni nanoparticles were formed in two different PMMA@PHEMA micelles, namely Ni-loaded PMMA(10K)@PHEMA(5K) and Ni-loaded PMMA(12K)@PHEMA(34K) which resulted in the distinctive differences in Ni content as well as the sizes of Ni nanoparticles. Besides the concentration of the catalyst, the reduction rate of 4-NP depended on PMMA@PHEMA micelle structure, i.e., higher catalytic activity was observed for Ni-loaded PMMA(10K)@PHEMA(5K). More importantly, the catalytic performance of Ni-loaded PMMA(12K)@PHEMA(34K) was markedly improved with increasing amount of PHEMA-shell crosslinker despite a reduction of Ni content in the micelles.