Flexible Phase Change Films with Hybrid AlN/Al2O3 Thermal Conduction Networks for Temperature Regulation

Abstract Phase change materials (PCMs) have attracted considerable interest in the thermal management of modern electronic devices, owing to their high heat storage density and nearly isothermal phase transition behavior. However, conventional PCMs are constrained by liquid leakage, mechanical brittleness, and low thermal conductivity. Herein, we report a flexible, shape-stable, and electrically insulating solid−solid phase change film (PCF) with enhanced thermal conductivity, fabricated by incorporating geometrically complementary phonon-conducting fillers (AlN and Al2O3) into a phase change polyurethane (PU) matrix. The cross-linked polymer network within PU not only ensures the shape stability of the PCF, but also endows the material with excellent mechanical flexibility and a latent heat storage capacity of 22.2 J/g. The resulting PCF-4 exhibits a thermal conductivity of 3.3 W·m−1·K−1 and a high-volume electrical resistivity of 5.56 × 108 Ω·m, ensuring reliable electrical insulation for electronic packaging applications. Additionally, the PCF shows a thermally triggered shape memory effect, which facilitates conformal interfacial contact and allows for physical recyclability. In a practical demonstration using a high-power LED module, the synergistic effect of rapid phonon transport and latent heat buffering reduces the core junction temperature by 32.4 °C compared with the case without thermal management. This work offers a sustainable, safe, and efficient strategy for thermal management in next-generation precision electronics.