Facile Green Strategy of Fabricating Flexible Phase Change Fibers with High Thermal Energy Capacity

The development of high-performance phase change fibers (PCFs) represents a significant advance toward achieving intelligent wearable thermal management for humans. However, existing PCFs are limited by a lot of drawbacks, such as low energy storage capacity, poor flexibility, and complex preparation processes. Here, we developed an efficient and simple methodology for the preparation of PCFs utilizing a green wet-spinning technique. The PCFs are composed of discontinuous octadecane microcapsules (M18) and a polymer matrix (sodium alginate), endowing the PCFs with excellent flexibility. Additionally, the fibers exhibit a high energy storage capacity of up to 113.2 J/g, demonstrating a marked improvement over the thermal energy storage capacities of currently available commercial thermoregulating fibers. The PCFs also present excellent shape stability above their melting temperature, confirming their potential for practical applications. Remarkably, colored PCFs could be obtained by incorporating minor quantities of dyes into the spinning solution, thereby improving their practical value. The outstanding thermal cycling stability of the PCFs was confirmed by their maintained enthalpy after they underwent 100 thermal cycling tests. In a subsequent investigation, graphene composite PCFs were prepared and evaluated for their thermal management efficacy, revealing their superior thermal management capabilities. Our findings contribute valuable insights for the research community and manufacturers toward a simplified and efficient production of flexible, high-performance PCFs with broad application potential.