(393h) Synthesis and Characterization of Temperature-Responsive VO2/PNIPA Nanocomposite Hydrogels

VO₂ has attracted much attention as a thermochromic material for smart windows because of its ability to transmit the near-infrared irradiation in winter and block most of it in summer while maintaining visible transmittance. In this paper, nanocomposite hydrogels of VO₂ and Poly(N-isopropylacrylamide) (PNIPA) were prepared by in-situ polymerization. VO₂ nanoparticles (~ 50 nm) with the light regulation capability of about 25% in the wavelength range from 350 nm to 1350 nm were synthesized by a hydrothermal method. The visible transmittance value of PNIPA is more than 50% at 25 °C and less than 10% at 80 °C. VO₂ with the weight 0.5%, 1% and 2% of NIPA were dosed and dispersed in water before polymerization. Results showed that VO₂ did not change the lower critical solution temperature of the PNIPA hydrogel. As increasing VO₂ content, the viscosity of hydrogel increased, which implied that VO₂ probably played a role as crosslinker as well as filler in the reaction. The nanocomposite hydrogels showed excellent stability and satisfactory light modulation efficiency.