Polymer dispersed liquid crystals-impregnated switchable thermochromic transparent woods with excellent ultraviolet blocking performance for smart windows

Due to the damage caused by ultraviolet (UV) radiations, the development of smart windows with UV-shielding capability is urgently needed to help reduce the aging of household items and protect human health. Traditional glasses exhibit inferior UV- and heat-shielding properties. Therefore, constructing alternative materials with high transparencies, low thermal conductivities, and excellent UV-blocking capabilities is significantly important to replace traditional glasses. Herein, switchable thermochromic transparent woods (TWs) are fabricated for smart windows using UV-curable polymer dispersed liquid crystal (PDLC) into modified woods for the first time. Thermochromic TW filled with PDLC (PDLC/TW) adjusts its visible light transmittance based on temperature without additional energy. Balsa PDLC/TW demonstrates a gradually increasing transmittance (from 28% at room temperature to 78% at 40°C) at 550 nm. Moreover, balsa PDLC/TW exhibits outstanding UV-blocking performance and almost five times lower thermal conductivity (0.197 W m^{− 1} K^{− 1}) than that of the glass (0.911 W m^{− 1} K^{− 1}). As-prepared PDLC/TWs can effectively allow the passage of visible light and block UV light during the day, which is beneficial for indoor illumination and human health. Interestingly, at night, they become opaque, thereby protecting privacy. These findings highlight the considerable potentials of PDLC/TWs for application in next-generation energy-efficient buildings.