Flexible Core–Sheath Composite Phase Change Thermoregulation Fiber Films via Coaxial Electrospinning

Composite phase-change thermoregulatory fiber films were successfully fabricated using coaxial electrospinning, with polyacrylonitrile fiber films serving as the sheath and octadecane as the core phase-change material. The optimized phase-change fiber films, produced at a sheath feed rate of 0.60 mL/h and a core feed rate of 0.25 mL/h, exhibited the ability to absorb, store, and release thermal energy within the human comfort temperature range (approximately 28 °C), achieving a high melting enthalpy of 171.6 J/g, indicative of excellent heat storage capacity. Moreover, these fiber films demonstrated outstanding thermal stability, retaining a latent heat of 117.7 J/g after 100 heating–cooling cycles, along with excellent mechanical properties, including a tensile strength of 2.418 MPa, tensile yield stress of 2.331 MPa, tensile strain at break of 36.5%, and an elastic modulus of 58.226 MPa. The films also exhibited an exceptional thermal management performance. This study introduces a promising phase-change material for advanced applications in smart textiles, enabling efficient temperature regulation and energy conservation while ensuring comfort during wear.