A structural polymer for highly efficient all-day passive radiative cooling.

Abstract in brief

• The study introduces a specially designed PMMA film with a hierarchical porous structure, including micropores and nanopores, which enhances its ability to reflect sunlight and emit heat, making it highly effective for passive radiative cooling both day and night.
• The film achieves high solar reflectance (0.95) and thermal emittance (0.98), allowing it to cool surfaces by up to 8.2°C below ambient at night and between 6°C to 8.9°C during the day under strong sunlight, even in hot and humid conditions.
• The porous architecture is essential in boosting the film's cooling performance, enabling it to be a low-cost, efficient solution for all-day, all-climate passive cooling applications.]