Phase change material-integrated Janus fabric with radiative cooling/solar heating for adaptive thermal management

As global energy demand rises and climate change intensifies, sustainable and energy-efficient thermal regulation solutions are attracting significant attention. Radiative cooling and solar heating offer passive temperature control without external energy input. However, their unidirectional nature (either cooling or heating) limits adaptability to varying environmental conditions. In this study, a dual-mode Janus composite fabric was developed to enable reversible radiative cooling and solar heating for adaptive thermal management. The asymmetric architecture features a cooling side (porous Poly (vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP)/hexagonal boron nitride (h-BN)/Paraffin (Pn)@silicon dioxide (SiO 2 )) achieving 96.24 % solar reflectance and 94.78 % IR emissivity. The heating side (multi-walled carbon nanotubes (MWCNTs)/sericin) exhibits 94.23 % solar absorptivity. Thanks to its excellent spectral properties, this Janus fabric demonstrated excellent solar heating performance (39 °C) and passive radiative cooling effect (10 °C) under sunlight compared to original cotton fabrics. Furthermore, the encapsulated PCMs (Pn@SiO 2 , Δ H m  = 179.4 J/g) provided a thermal buffer platform during heating and cooling periods, effectively mitigating sudden temperature changes. Additionally, the Janus fabrics demonstrated outstanding flexibility, air permeability, and hydrophobic easy-cleaning properties. These findings suggest that this work could provide a sustainable, energy-free solution for adaptive thermal management in dynamic climatic environments.