Janus-type flexible phase change composite for wearable thermal management and electromagnetic interference shielding

Phase change materials (PCMs) are promising candidates for facilitating zero-energy thermal management on account of their constant phase-transition temperatures and excellent thermal storage capacity. However, low thermal conductivity, solid-state rigidity, and weak electromagnetic interference (EMI) shielding effectiveness are long-standing challenges limiting PCM-based wearable thermal regulation for portable flexible electronic devices. Herein, a Janus-type flexible phase change composite film is fabricated via a simple and low-cost phase inversion and direct spraying strategy, which incorporates an innovative combination of graphene nanoplatelets-cobalt nanoparticles@polyvinylidene fluoride (GNP-Co@PVDF) as the porous skeleton and MXene@polytannin acid (PTA) as the sprayed layer. Resultantly, the tailored flexible composite film achieves a 960% improvement on thermal conductivity relative to paraffin, coupled with prominent EMI-shielding performance of 38.9–62.5 dB and desirable enthalpy density of 146.9 J·g⁻¹. Besides, this film also exhibits leakage-resistant property, multi-source-driven thermal responsiveness, shape memory feature, and robust cyclic stability. These integrated performances substantially broaden its application potential for advanced thermal management of smart portable electronics.