Polymer‐Based Passive Radiative Cooling A Structural Design Perspective

ABSTRACT Passive radiative cooling (PRC) offers a sustainable pathway for heat dissipation to outer space without energy input. Polymers have emerged as attractive platforms owing to their lightweight, flexibility, low cost, and structural tunability. This review highlights structure‐oriented strategies for polymer‐based PRC, categorized into fibrous, porous, photonic/meta, and hybrid composite designs. Fibrous networks enhance solar scattering while maintaining breathability; porous systems utilize multi‐scale pores for strong reflectance and broadband infrared emission; photonic/meta‐structures enable spectral selectivity and color control; and hybrids integrate inorganic fillers to achieve robustness and multifunctionality. Representative studies report solar reflectance above 98%, emissivity above 97%, and net cooling powers exceeding 100 W·m ⁻² under daytime conditions. Beyond performance, advances in eco‐friendly polymers, humidity‐tolerant structures, and scalable fabrication are emphasized. General design principles are summarized within a structure–property–performance framework, stressing broadband solar scattering, efficient IR emission, scalable processing, and interfacial engineering. Remaining challenges include balancing color with cooling efficiency, establishing standardized evaluation protocols, and ensuring durability for practical applications. This review outlines pathways for transitioning polymer‐based PRC from laboratory research to large‐scale deployment in buildings, textiles, and emerging technologies. image