Thermochromic Bilayer Nanofibrous Membrane with Temperature-Triggered Radiative Cooling/Solar Heating and Unidirectional Moisture Transport for Personal Thermohygroscopic Management.

Conventional textiles are limited by static thermal-regulation mechanisms and inadequate body-surface sweat management. To address these challenges, a temperature-triggered bilayer nanofibrous membrane was fabricated via sequential electrospinning for the synergistic thermohygroscopic management of the human microclimate. The composite membrane consisted of a hydrophilic cellulose acetate/polyethylene glycol outer layer doped with thermochromic microcapsules (CA/PEG/TCM) and a hydrophobic poly(lactic acid)/zinc oxide inner layer (PLA/ZnO). When strong solar irradiation raised the membrane temperature above the preset transition temperature of TCMs at 38 °C, the membrane passively changed from the colored state to the faded state, showing both visible reflectance and atmospheric-window emissivity above 90%. Particularly, the blue membrane delivered a theoretical cooling power of 65 W m-2 and achieved a temperature reduction of 8.1 °C compared with cotton fabric under outdoor sunny conditions with strong solar irradiation (629 W m-2). By contrast, under lower solar irradiation and lower membrane temperature, the colored state was retained, suppressing visible reflectance and enhancing solar absorption, which increased the temperature by 2.6 °C compared with cotton fabric. In addition, the asymmetric wettability of the structure enabled spontaneous unidirectional moisture transport from the skin-contact side to the external environment, while the incorporated ZnO nanoparticles imparted antibacterial activity to the inner layer, showing an antibacterial rate approaching 100% against Escherichia coli. Overall, this thermochromic bilayer nanofibrous membrane provides a feasible approach for integrating passive temperature-triggered radiative cooling/solar heating with moisture management and antibacterial protection for personal thermohygroscopic comfort under different solar irradiation intensities.