Solid-solid phase change fibers with enhanced energy storage density for temperature management

Solid-solid phase change fibers are advantageous for thermal management and latent heat storage , because they don't have the issue of liquid leakage facing those common ones that have a solid-liquid phase-transition. However, the relatively low heat density hinders such fibers from real applications. Herein, we report a strategy to fabricate solid-solid phase change fibers with much enhanced energy storage density , through coaxial wet spinning using thermoplastic polyurethane solution and polymerizable polyethylene glycol solution as outer spinning solution and inner spinning solution, respectively, followed by light-driven radical polymerization . The resulting fibers exhibited good flexibility and good tensile performances, with elongation at break and breaking strength of approximately 629.1 % and 3.8 MPa, respectively. Moreover, the fibers showed quite high heat density of 122.5 J/g, much higher than that of the previously reported phase change fibers with a solid-solid phase-transition, and high reusability , with heat density of 102.0 J/g preserved after 100 heating-cooling cycles. These attractive features make the fibers to be promising for wearable temperature management, energy harvesting and heat storage applications.