Bio-based intrinsic flame-retardant phase change material derived from vanillin

This study addresses the flammability issue of paraffin-based phase change materials (PCMs) and the limitations of most additive flame retardants that fail to exhibit effective flame-retardant properties. Based on the phase change mechanism and chemical structure of paraffin-based PCMs, a novel “composition-structure-function integration” design concept for intrinsic flame-retardant PCM (VOD) is proposed. The synthesized VOD integrates phase change groups with “acid source, carbon source, and gas source.” The phase-change energy-storage performance, thermal stability, and flame-retardant properties of VOD were investigated. The melting enthalpy and crystallization enthalpy of VOD are 59.4 J/g and − 59.2 J/g, respectively. The thermal stability of VOD is significantly superior to that of octadecylamine (ODA), with residual char content reaching 17.1 wt% and 19.6 wt% under nitrogen and air atmospheres, respectively. VOD exhibits remarkable flame-retardant behavior, achieving self-extinguishing within 30 s of ignition. Compared to ODA, its peak heat release rate decreases by 69.9 %. The gaseous pyrolysis products of VOD are analyzed using thermogravimetric-infrared spectroscopy and pyrolysis-gas chromatography–mass spectrometry. Combined with the analysis results of the char layer, the flame-retardant mechanism of VOD is elucidated. This work opens a new research direction for the synthesis of biomass-based PCMs and provides a theoretical foundation and solutions for the scientific design of intrinsic flame-retardant PCM molecular structures.