Thermosensitive Core-Shell Microgel as a “Nanoreactor” for Metal Nanoparticles

In our study, thermosensitive core-shell microgel particles have been used as the carrier system for the deposition of metal nanoparticles, in which the core consists of polystyrene (PS) whereas the shell consists of poly(N-isopropylacrylamide) (PNIPA) network crosslinked by N, N'-methylenebisacrylamide (BIS). Silver, gold and palladium nanoparticles have been homogeneously embedded into thermosensitive PNIPA-networks, respectively. We demonstrate that the catalytic activity of the microgel-metal nanocomposites can be tuned by the volume transition within the microgel of these systems by using the catalytic reduction of 4-nitrophenol as the model reaction. Moreover, following the concept of a “green chemistry”, the oxidation of alcohols to the corresponding aldehydes or ketones can be carried out in aqueous solution under aerobic conditions at room temperature by using microgel-metal nanocomposites as the catalyst. The influence of temperature on the catalytic activity has been also investigated, which will be affected both by the volume transition of the microgel and by the change of polarity of the microgel in this case.