An Intrinsically Flexible Phase Change Film for Wearable Thermal Managements

Abstract Phase change materials (PCMs) involving significant amounts of latent heat absorbing and releasing at a constant transition temperature have been extensively utilized for thermal management of electronic devices. However, it is still a great challenge to apply thermal management for wearable devices using PCMs due to their solid rigidity and liquid leakage. Although considerable efforts have been dedicated to constructing flexible composite PCMs by physically blending bulk PCMs with different flexible polymers, design and fabrication of intrinsically flexible PCM films still remain unexplored. Herein, we report an intrinsically flexible PCM film with apparent solid-solid phase transition performance, outstanding self-support and shape-conformable property for wearable thermal management. Remarkably, the as-obtained PCM film behaves adjustable phase transition enthalpy and temperature in the region from about (5 to 60)°C, long-term cycling stability up to 1000 cycles, highly mechanical flexibility and remarkable shape tailorability and foldability. Notably, such flexible PCM films are easily integrated into wearable devices with a flexible graphene film as thermal source, revealing superior temperature control behaviors, together with unprecedented electro-thermal and photo-thermal energy conversion performance. The intrinsically flexible PCM film developed in this work is holding great potential for next-generation flexible thermal management electronics.