Investigation of Ag nanoparticles loading temperature responsive hybrid microgels and their temperature controlled catalytic activity

Silver (Ag) nanoparticles loading temperature responsive hybrid microgels were readily prepared by in situ reduction of Ag+ ions coordinated into poly(N-isopropylacrylamide) microgels. The weight percentage content of the entrapped Ag nanoparticles measured by thermogravity analysis tops 25%, and their average particle sizes determined by transmission electron microscopy are within the range from 8 to 11 nm. The results obtained by X-ray diffraction exhibit that the Ag nanoparticles are of face-centered cubic single crystal structure. The particle sizes of the hybrid microgels decrease sharply with environmental temperature increasing from 30 to 35 °C, and their surface plasmon resonance absorption wavelengths are pronouncedly red-shifted within the same temperature range. The catalytic reactivity of the Ag nanoparticles loading hybrid microgels can be tunable with four stages of change versus temperature from 20 to 45 °C.