Reversibly thermochromic and high strength core-shell nanofibers fabricated by melt coaxial electrospinning

Recent years, phase change materials (PCMs) with potential to store and transform energy have attracted broad attention, especially in the field of thermal energy storage. However, the instability and leak proneness of PCMs limit their universal application. In this paper, core-shell fibers with 1-tetradecanol (TD) as core and poly(vinylidene fluoride) (PVDF) as shell were prepared via melt coaxial electrospinning method, and for improvement, the dye composed of crystal violet lactone (CVL) and bisphenol A (BPA) was added to the core to endow the fiber the function of reversible thermochromism. During the preparation process, it was found that the addition of NaCl could regulate the fiber morphology and strength its mechanical property. By adjusting the concentration of shell solution and the flow rate of core solution, the high-strength reversible thermochromic fibers were produced when polymer concentration was 24 wt% with a core feed rate of 0.4 ml/h. The latent heat of these fibers is up to 88.71 J/g. Besides, its color can change from blue to white when heated, and the transition temperature is around 38°C. And 100 thermal cycle tests of the fiber showed its strong thermal stability and thermochromic property.