A thermochromic poplar-based tetradecyl ester/methyl composite encapsulated with PEG400–SiO2 (PS-R-PTC) for improving thermal energy storage

Abstract

Thermochromic wood is an important research direction for wood modification in recent years, and a red poplar-based thermochromic composite (R-PTC) had been prepared in our previous study by compositing a mixture of phase change reagents (tetradecyl ester: C₂₈H₅₆O₂ and methyl red: C₁₅H₁₅N₃O₂) and full poplar wood. In order to improve the heating storage ability of R-PTC and encapsulating phase change reagents to prevent leakage, a new R-PTC composite (PS-R-PTC) was prepared by encapsulated R-PTC with polyethylene glycol 400 (PEG400)–SiO₂ in this work. Compared to the original R-PTC samples, the cell walls of PS-R-PTC were not significantly changed by the SiO₂ film and we also found that PS-R-PTC with PEG400 (90%)–silica solutions (10%) mixture had better heat storage performance and PS-R-PTC (90%) has better enthalpy change value (R-PTC: 43.01 J g⁻¹; PS-R-PTC (90%): 71.82 J g⁻¹). The PS-R-PTC can show the function of thermal energy storage, which is used in wooden buildings and can be a feasible insulating material for reducing thermal energy losses and hence reducing energy usage. In PS-R-PTC, SiO₂ combines with the –OH of the R-PTC and the –OH of PEG400 (HO(CH₂CH₂O)_nH), and these –OH lose hydrogen ions too.