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.
