An ultrastrong wood-based phase change material for efficient photothermal conversion and thermal energy conservation

Phase change material (PCM) with outstanding thermal energy storage and temperature regulation, holds tremendous interest in energy conservation and management. However, the application of conventional PCMs is limited due to issues of liquid leakage, poor mechanical properties, and insufficient photothermal conversion efficiency. In this work, inspired by the powerful muscle system, we developed a shape-stable PCM via in-situ polymerization of polyurethane in the wood. This wood-based PCM could reach a tensile strength of 96.5 MPa along the longitudinal direction, up to 3-50 times that of reported PCMs, due to a unique aligned fiber array and energy dissipation system. Meanwhile, this composite had a high enthalpy of 95.4 J/g and a photothermal conversion efficiency of 83.2 %. It is believed that such an eco-friendly and ultrastrong wood-based PCM with efficient solar energy utilization will be a novel option for building energy collection, storage, and regulation.