Bioinspired Segregated Networks Couple Phase-Change Confinement With Ultrafast Sensing for Thermal Energy Storage.

Harvesting ambient renewable energy requires materials that can retain their function under coupled and often harsh environmental conditions. Flexible phase-change materials (PCMs) are promising for wearable systems because they can integrate thermal regulation, physiological sensing and energy harvesting. Here, inspired by the hierarchical architecture of rice leaves, we report a phase-change elastomer for ambient energy harvesting and ultrafast moisture sensing, fabricated via an in situ biomimetic assembly strategy. A continuous 3D segregated network of carboxymethyl chitosan coordinated with Cu2+ ions spatially confines polyethylene glycol (PEG) within a poly(ethylene vinyl acetate) (EVA) matrix. This biomimetic network enables a toughness of 9.80 MJ m-3 and an elongation at break of 218%. Unlike conventional PEG composites that are prone to humidity-induced instability, the elastomer exhibits enhanced moisture resistance and a reduced leakage rate of 1.46%. Continuous ionic pathways within the segregated network enable an ultrafast humidity response of 172 ms, whereas the Cu2+-containing network provides broad-spectrum antibacterial activity. This work establishes a biomimetic strategy for designing multifunctional phase-change elastomers for wearable energy harvesting and environmental sensing in complex operating conditions.