Novel Photothermochromic Smart Window Based on PNIPAm‐glass‐MXene/PAM with High Shield, Fast Response, and Excellent Stability

In recent years, smart windows have emerged as an important method to achieve energy efficiency in buildings. The responses of thermochromic smart windows are very dependent on the photothermal absorption of nanoparticles. However, nanoparticles dispersed in thermochromic materials cause high thermal loads on the window's surface and become nonuniform and unstable with time. These problems seriously limit application of photothermochromic smart windows. Herein, a new photothermochromic smart window is designed using bicomponent poly ( N ‐isopropylacrylamide) PNIPAm and MXene/polyacrylamide (PAM), denoted as P‐g‐M smart window. Compared with other photothermochromic smart windows, the developed P‐g‐M smart window reduces the window's surface temperature, and there is no obvious visibility decrement due to the long‐term stable dispersion of MXene. The small particle size of PNIPAm microgels synthesized by the one‐step method shows high scattering efficiency, and the fabricated 1‐mm PNIPAm displays 91.2% visible light transmittance and 99.2% solar light shielding. While pursuing efficient light management, the P‐g‐M smart window responds 25 min faster than a 1 mm PNIPAm smart window. In addition, the device effectively improves the hydrogel thermal response stability. The indoor and outdoor energy‐saving demonstration shows that P‐g‐M smart windows can reduce indoor air temperature by 5–10 °C compared with normal windows.