Tailored light-colored polyamide 6/66 and cesium tungsten bronze composite fabrics for efficient photothermal conversion

Cesium tungsten bronze (Cs_0.33WO₃) exhibits strong absorption in the near-infrared (NIR) region of solar radiation while maintaining high transparency in the visible spectrum. By uniformly incorporating nanoscale Cs_0.33WO₃ particles into a fiber matrix, it is possible to fabricate light-colored, aesthetically pleasing, photothermal textiles that enhance human thermal comfort in cold environments. However, the high surface energy of nanoscale Cs_0.33WO₃ particles impedes their homogeneous dispersion within the fiber matrix, posing a significant challenge for industrial-scale production. Herein, we modified the Cs_0.33WO₃ nanoparticle surfaces with polyvinylpyrrolidone (PVP) to enable uniform dispersion in a polyamide 6/66 (PA6/66) matrix and employed a scalable melt-spinning technique to produce PA6/66-Cs_0.33WO₃ composite fibers. The resulting PA6/66-Cs_0.33WO₃ composite fibers exhibit excellent mechanical strength of up to 3.0 cN/dtex, enabling their large-scale conversion into composite fabrics. Owing to the strong NIR absorption of Cs_0.33WO₃, the light-colored fabric achieves a high average solar absorptance of up to 77 %. Under midday sunlight, the surface temperature of the PA6/66-Cs_0.33WO₃ composite fabric was recorded to be 21.7 °C higher than the ambient temperature and 9.1 °C higher than that of the pristine PA6/66 fabric. This light-colored photothermal fabric exhibits great potential in thermal-responsive applications, particularly as an outer-layer material for gloves and down jackets, where it facilitates heat generation through light absorption.