Bioinspired composite fibrous membranes with phase-change radiative cooling for all-weather personal thermal management

Daytime radiative cooling offers a passive, energy-free pathway for personal thermal management, but nighttime overcooling remains a critical challenge. Inspired by the hierarchical structure of silkworm cocoons, we design a multifunctional composite fibrous membrane featuring a well-defined core-shell heterostructure via one-step coaxial electrospinning. A poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) shell encapsulates a n-octadecane phase-change core, integrating radiative cooling with thermal energy storage in a single composite system. The PVDF-HFP shell provides strong Mie scattering and high mid-infrared emissivity via its micro-/nanofibrous structure and C–F vibrations, while the PCM core delivers thermal buffering through reversible latent-heat exchange during solid-liquid transition. A honeycomb-like corrugation on the membrane surface creates a micro-scale and concave-convex topography, boosting solar reflectance and thermal regulation. This composite design achieves excellent radiative cooling performance (solar reflectance \(\:{{-}{R}}ₛₒₗₐᵣ\) =97.2%, infrared emissivity \(\:{{-}{ε\:}}IR\) =94%), high latent heat storage/release capacity (∆ H c =122.6 J/g, ∆ H m =122.86 J/g), good thermal stability and thermal buffering capacity, and superior wearing comfort. Moreover, the core-shell interface effectively ensures leakage-free performance even after repeated thermal cycling, while the structured surface imparts hydrophobicity (water contact angle = 137.3°) and mechanical robustness (4.38 MPa). Outdoor tests further confirm the synergistic effect of daytime cooling (7.6 °C reduction vs. ambient) and nighttime overcooling suppression, validating efficient all-day thermal management. This work offers a composite materials design strategy for all-weather thermal regulation, with promising applications in energy-saving personal comfort and building thermal management.