Temperature Self‐Regulation, Energy Storage, and Fire Safety Intelligent Wood for Safe and Energy‐Efficient Buildings

ABSTRACT With the intensification of the global energy and environmental crises, organic phase change energy storage materials (OPCM) are widely used in energy efficient buildings. However, conventional OPCM are easily flammable and prone to leak, which restricts their applications in emerging fields. Herein, a novel intrinsic flame retardant OPCM (bis (polyethylene glycol) methyl phosphonate, BPMP) was successfully synthesized by the nucleophilic substitution reaction of polyethylene glycol (PEG) and methyl phosphorus dichloride. Compared with conventional OPCM, BPMP is almost incapable of being ignited and maintains a phase change latent heat (153.57 J/g) similar to that of PEG. Subsequently, flame‐retardant energy‐storage transparent wood (FOPTW) was prepared by vacuum pressure impregnation of BPMP into the delignified cellulose frame. Due to the capillary action and intermolecular hydrogen bonding of wood stencil, FOPTW exhibited excellent leak resistance and reinforcement properties. The enthalpy of FOPTW was up to 77.23 J/g with only minor changes after 50 cycles. Meanwhile, FOPTW can realize the immediate extinguishment effect from fire, and its rate and total amount of heat release are 17% and 50.7% lower than those of OPTW. It is attributed to the gas‐phase radical trapping and condensed‐phase catalytic charring effect of BPMP in FOPTW. Meanwhile, the phase transition latent heat process of FOPTW is used to embed temperature sensors inside it and construct thermal runaway warning devices, thus realizing active and repetitive high temperature warnings for OPCM. This bio‐based energy storage material with multiple fire safety protection systems provides a novel design idea for creating intelligent, green, and safe buildings in the 21st century.