Preparation and Catalytic Performance of Surface-covered AuNPs@PNIPAM Composite Particles

Gold nanoparticles (AuNPs) with high surface energy are easy to agglomerate in water, which restricts their applications. In this study, poly (N-isopropyl acrylamide) (PNIPAM) microgel and AuNPs were combined by electrostatic interaction through physical blending method inorder to cause negative citrate-stabilized AuNPs absorbed on the surface of positive PNIPAM microgels. The prepared surface-covered AuNPs@PNIPAM particles not only have excellent dispersion stability, but also exhibit a temperature-dependent colorimetric property, showing a reversible change of "red -> purple -> red" during the temperature change of 2 degrees C5 -> 50 degrees C -> 25 degrees C. In addition, the p-nitrophenol (4-NP) reduction reaction was used as the simulated catalytic reaction to examine the catalytic performance of AuNPs@PNIPAM. The results showed that the catalytic performance of AuNPs@PNIPAM first decreased and then increased with temperature. Compared to similar materials reported in the literature, the AuNPs@PNIPAM showed both temperature-colorimetric properties and catalytic performance.