Intrinsically Flexible Polyurethane-Based Phase-Change Composites with High Heat Storage Density for Thermal Management Applications

Phase change materials (PCMs) with high energy storage density and good flexibility are ideal for human therapy and thermal management. To overcome the common drawbacks of leakage and limited flexibility in conventional PCMs for wearable therapy, inherently flexible polyurethane-based phase change materials (PUPCMs) were first synthesized with a cross-linked network structure via a prepolymer method. To further enhance the energy storage capacity, a series of flexible phase change composites (FPCCs) with high energy storage density, outstanding flexibility, and stable shape retention were developed using a dual-encapsulation strategy. The potential of these FPCCs in personal thermal management was also systematically investigated. The 15%FPCC sample exhibited a melting temperature of 38.2 °C and a latent heat enthalpy of 97 J/g. Moreover, the composite demonstrated superior morphological stability, reliable cycling performance, and significantly improved heat storage and temperature regulation capabilities. Infrared thermography experiments confirmed the conformability of the material on various body regions, highlighting its promising thermal comfort and practical applicability. The as-prepared FPCCs integrate excellent phase change energy storage performance with remarkable flexibility and shape stability, thereby paving the way for the design, fabrication, and application of advanced flexible PCMs.