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Functionalized smart fabrics based on phase change materials (PCMs) are potential candidates for adaptive temperature regulation. In this work, composite PCM (CPCM) was first designed with optimized thermophysical properties and antileakage performance. Magnesium oxide (MgO) whiskers were used as the thermal filler to enhance the heat conduction of the CPCM. To improve the compatibility between the filler and the matrix, the whiskers were encapsulated by polystyrene (PS) hollow fibers, forming nanostructured MgO@PS fibers, accompanied by reduced interfacial thermal resistance (ITR). The composite phase change fabric (CPCF) with uniformly distributed internal composition was prepared by the vacuum impregnation method. Owing to the optimized CPCM matrix and specifically designed MgO@PS nanostructure, the final developed fabric (CPCF-M8) showed favorable phase change properties, good stability and mechanical properties, and excellent thermal conductivity of 1.34 W/mK (a 434% improvement compared to the original CPCM). The efficient thermoregulation capability of the CPCF-M8 was further confirmed by performing the practical human thermal management tests with a maximum temperature adjustment of 2.3 °C. In addition, the outdoor temperature adaption tests revealed that the CPCF-M8 was able to provide self-cooling and self-heating, resulting in a maximum 4.2 °C temperature adjustment.

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.

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