Daytime radiative cooling has emerged as a promising passive strategy for sustainable thermal management, yet its widespread implementation remains hindered by the lack of colorful, transformable, and scalable material systems. Here, we present a new class of structurally colored radiative cooling fibers created by microfluidic extrusion of mid‐infrared (mid‐IR)–emissive colloidal structural fluids. These fluids consist of monodisperse silica (SiO 2 ) nanoparticles (NPs) suspended in an acrylate resin, which self‐assemble into amorphous photonic glass during microfluidic shear flow and are subsequently solidified by in situ photocuring. The resulting fibers exhibit angle‐independent and permanent structural coloration across the visible spectrum, which is tunable via NP size and interparticle spacing without the use of pigments or dyes while maintaining broadband mid‐IR emissivity (>0.9) arising from SiO 2 phononic vibrations. When woven into fabrics, these photonic fibers combine high solar reflectance with strong mid‐IR thermal emission, enabling effective reduction of solar heat gain and daytime cooling of a heated skin‐mimicking substrate even under direct sunlight. Outdoor tests confirm that photonic glass textiles achieve a large temperature depression on simulated skin phantoms, consistent with their broad visible scattering and high mid‐IR emissivity. This work introduces a scalable and esthetically versatile route toward colorful radiative‐cooling textiles, bridging photonic design with practical energy‐saving applications in outdoor and wearable systems.
Ahn et al. (Wed,) studied this question.