Polyamide 6-Al2O3 nanoparticle composite nanofiber membranes with high solar reflectivity and human radiation transmittance for passive human body cooling

Passive radiant heat management is an energy-saving thermal radiation management technology that can improve the temperature regulation of conventional clothing in high-temperature environments. However, existing materials are either complex in structure, difficult to fabricate, or unsuitable for human application. In this study, a novel nanofiber membrane was developed that exhibits high solar reflectance and infrared transparency to human radiation, thus having an excellent radiative cooling effect. The nanofiber membrane was prepared by electrospinning polyamide (PA) 6 containing Al₂O₃ nanoparticles. It exhibits an average solar radiation reflectance of about 88 %, a maximum reflectance of more than 95 %, and transmittance to the human body infrared of more than 95 % and provides a cooling effect of 4–6.4 °C for outdoor objects (with convection), which results from the coaction of PA6 nanofibers and Al₂O₃ nanoparticles. The implementation of nanofiber membranes in clothing could not only protect wearers from high outdoor temperatures but also improve air and moisture permeability. We hope that this unique nanofiber membrane will be useful for managing thermal comfort and energy efficiency in various applications ranging from architectural materials to personal cooling solutions.