Sustainable Radiative Cooling of Microstructure Modulated Flexible poly(lactic Acid) Films

The optimization of polymer microstructures to enable resonant light scattering within the solar spectrum offers significant potential for passive cooling, however, achieving precise microstructural control remains technically challenging. Herein, we present a strategy for fabricating polylactide radiative cooling film with adjustable microstructure. The surface pore structure and internal spherical structure of the film are precisely controlled by polyethylene glycol, which in turn modulates the film's optical properties. This enables the film to achieve a cooling power of 50.4 W·m^-2 under a solar irradiation intensity of 820 W·m^-2, resulting in an average temperature reduction of 5.2 °C during the day and 7.6 °C at night. Additionally, the film could achieve a tensile strength of 3.84 MPa, an elongation at break of 32.1%, and paper-like flexibility for effortless bending. These results highlight the potential of the film for diverse applications in construction and equipment cooling, offering an environmentally sustainable solution for next-generation flexible radiative coolers.