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) n H), and these -OH lose hydrogen ions too.