Cs _0.33 WO ₃ ‐TiO ₂ Integrated Poly(N‐Isopropylacrylamide)/Gelatin Based Thermoresponsive Copolymeric Hydrogels with Tunable Optical Properties for Smart Windows

ABSTRACT The regulation of solar radiation and near infrared (NIR) radiation has been a significant challenge in buildings and automobiles for energy conservation. pNIPAM hydrogel‐based smart windows have challenges like stability issues, low NIR shielding capability, poor film‐forming ability, and are not viable for energy savings in liquid form. Herein, a stable and flexible thermoresponsive copolymer hydrogel film of pNIPAM, gelatin methacrylate (GelMA), and castor oil‐derived acrylated epoxidized methyl ester (CAME) with a tunable lower critical solution temperature (LCST) of 23.6°C–26.9°C is developed through free radical polymerization with reduced pNIPAM content to make it more green and sustainable. Cs _0.33 WO ₃ is synthesized through the microwave hydrothermal method (MWHM), and TiO ₂ is introduced to enhance its optical properties. The NIR shielding CWO‐TiO ₂ heterostructure is integrated into the copolymer, and the composite hydrogel exhibits visible light transmittance of 71.0%, solar modulation (∆T _sol ) of 42.1%, and NIR transmittance of 4.0% (above LCST). The composite hydrogel smart window reduces the indoor temperature up to a maximum of 8.8°C compared with conventional glass windows. The developed hydrogel with tunable visible light transmittance, NIR shielding potential, water stability, and flexibility paved a potential way for real‐time smart window applications.