Reversible Thermochromic Nanofiber Membrane for Energy Storage and Thermoregulation

Abstract

In this research, a series of reversible thermochromic nanofibrous membrane-containing phase change materials (RT-NFMPCMs) are fabricated successfully. The microstructure of RT-NFMPCMs with outstanding latent heat storage–release properties is modified and characterized systematically. The cores of RT-NFMPCMs comprise green dye GN-2 as a thermal colorant, bisphenol AF as a color developer, and n-butyl stearate as a cosolvent. The factors influencing the encapsulation process, for instance, shell solution concentration, core solution flow rate, and thermal cyclic stability, are characterized to clarify the effects of various experimental conditions. The surface morphology, core thickness, and core–sheath structure of RT-NFMPCMs are characterized by transmission electron microscopy (TEM) and thermal field emission scanning electronic microscopy (TFE-SEM). The fusion crystallization temperatures and enthalpies of RT-NFMPCMs are determined by differential scanning calorimetry (DSC) under different conditions. The thermal stability of RT-NFMPCMs is well illustrated by the properties of thermogravimetric (TG) measurements. In addition, the absorbance obtained using a spectrophotometer certainly allows visualization of the color change characteristics of RT-NFMPCMs as well. The experimental results demonstrate that a nanofiber membrane with a smooth surface and apparent core–shell structure is prepared successfully. With the increase of the core rate of RT-NFMPCMs, the enthalpy also increases accordingly within a certain range. Moreover, the encapsulation effect of the nanofibrous membrane is obvious, and the energy storage efficiency is 73.8%. The color change phenomenon of the prepared RT-NFMPCMs could be observed when the encapsulated n-butyl stearate undergoes a melting or crystallizing process, indicating that the fabricated RT-NFMPCMs present perfect thermochromic performance. Furthermore, the RT-NFMPCMs exhibit excellent stability because the latent heat is almost unchanged even after 100 heating–cooling cycles. Therefore, the RT-NFMPCMs developed in this study have a certain guiding significance for intelligent thermoregulatory textiles and other thermal regulation fields.