Flexible High-Thermal-Conductivity Phase Change Films via Electrospun Meta-Aramid Nanofibers and Boron Nitride Nanosheets for Thermal Management

The development of high-power-density equipment necessitates efficient thermal management. Phase change materials (PCMs), despite their high latent heat and isothermal operation, face application challenges due to low thermal conductivity, leakage, and poor flexibility. In this study, a flexible phase change film was successfully prepared by electrospinning meta-aramid nanofibers (PMIA) and poly(ethylene glycol) (PEG). The introduction of a small amount of boron nitride nanosheets (BNNS) as thermal conductive fillers constructed a continuous network within the fibers, which significantly enhanced the heat transfer capability of the composite. The composite film could achieve a relatively high thermal conductivity of 1.96 W/(m·K) and a phase transition enthalpy value of 59.5 J·g –1 with the addition of extremely low boron nitride (9 wt %). After 50 melt-curing cycles, the melting enthalpy and crystallization enthalpy only decreased by 1.2%, demonstrating promising cycle stability. Meanwhile, this composite film featured notable flexibility, with an elongation at break of 83%, and possessed good mechanical adaptability. This composite material shows promise for thermal management in high-power-density electronic devices and thermoelectric conversion systems.