Solvent-Free Nanofluid Laminated Films with Temperature-Adaptive Properties

Passive radiative cooling (PRC) has emerged as a promising zero-energy cooling strategy to alleviate energy shortages and environmental burdens. However, conventional static PRC materials inevitably suffer from supercooling, while most existing dynamic regulation strategies rely on external energy input or complex fabrication processes. This work realizes adaptive “radiative cooling− supercooling suppression” regulation without external energy input. An aluminum oxide solvent-free nanofluid (Al2O3-SNF) phase- change material, with a phase transition temperature (Tm) of 25.7 °C, was rationally designed to match human thermal comfort and environmental thermal management requirements. By integrating Al2O3-SNFs into porous poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] films (NPA) fabricated via a non-solvent-induced phase separation method, an adaptive laminate film (NPA/Al2O3-SNFs/NPA) was developed. Interestingly, the laminate film autonomously switches between radiative cooling and supercooling suppression near the Tm. Outdoor tests further reveal that the laminate film achieves a daytime radiative cooling temperature reduction of 4.3 °C while effectively suppressing nighttime supercooling through phase transition heat release, resulting in a minimal temperature drop of only 0.3 °C. Moreover, the film exhibits a water contact angle of up to 131.1°, indicating excellent hydrophobicity and self-cleaning performance. This work provides a feasible strategy for developing next-generation low-energy thermal management materials applicable to building energy efficiency and personal thermal management.