Transparent wood with thermo-reversible optical properties based on phase-change material

Many phase change materials experience a change in optical properties when undergoing a phase transition, showing great potential in preparation of smart optical materials. In this work, copolymer consisted of monomer styrene (St), butyl acrylate (BA), and 1-octadecene (ODE) was infiltrated into treated wood to obtain a flexible transparent wood (TW) with thermo-reversible optical properties (abbreviated as SBO/TW). The introduction of ODE chains induced obvious revisable endothermic decrystallization and exothermic crystallization behaviors, which indicated that SBO/TW had revisable optical characteristic. The novel phase-change SBO5/TW could repeatedly turn from opaque (similar to 23.7% of transmittance, similar to 98.3% of haze) to transparent (similar to 74.9% of transmittance, similar to 36% of haze) with an increase in temperature, and vice versa during the cooling process. In addition, the thermal conductivity of SBO/TW was lower than 0.2 W m(-1) k(-1), which is the limit value of thermal insulation material. Moreover, SBO/TW showed excellent flexibility with a high breaking elongation (similar to 80%) and low storage modulus (good softness). This study presents a synthetic strategy to control optical properties of TW, promoting the potential application of TW as smart light controlling systems.