Design and Construction of Photochromic and Antileakage Reinforced Wood-Based Cellulose Microframework/Hexadecanol-Coconut Oil Composite Phase Change Material.

The development of high-performance shape-stable phase change material composites (SPCMs) with high phase change enthalpy and high conversion efficiency, especially with good photochromic properties, is essential for thermal energy storage. Here, we report that one type of SPCMs with both photochromic and phase change energy storage is obtained by incorporating organic binary composite PCMs (hexadecanol/coconut oil, H/C) and photochromic phosphotungstic acid (PA) into Ochroma pyramidale wood-based cellulose microframe (DOW) through simple vacuum impregnation. When the ratio of hexadecanol to coconut oil is 3:7 and the ratio of phosphotungstic acid to ,-dimethylacetamide is 4:13.6, the SPCM composite material (DOW-H3C7-4PA) represents a high phase transition enthalpy of 163.7 J/g and an appropriate phase transition temperature of 42.55 °C that can be applied to the environmental temperature adjustment of high-temperature areas (>40 °C) mentioned in this paper, in addition to the excellent thermal stability and photochromic stability; for example, even after 100 thermal cycles and UV radiation cycles, its phase transition enthalpy remains almost unchanged. The DOW-H3C7-4PA composite material also shows good shape stability and leakage resistance. In addition, the high photothermal conversion efficiency (65.71%) of DOW-H3C7-4PA is considered to be a promising candidate for photothermal energy storage applications. Therefore, the manufactured SPCMs (DOW-H3C7-4PA) have high latent heat, good melting/freezing cycle reliability, high photochromic stability, and remarkable light-to-heat energy conversion ability, making them show broad application prospects in energy conversion and storage devices.