Flame retardant and form-stable phase change composites based on phytic acid/dopamine-decorated delignified wood for efficient solar-thermal energy conversion and storage

Herein, phytic acid/dopamine-decorated delignified wood (APDW) with superior photothermal effects and excellent flame retardancy was constructed by alkaline cooking delignification, dopamine self-polymerization and phytic acid-modification on the surface of delignified wood. Then, novel form-stable and flame-retardant phase change composites (ADPCMs) were fabricated by impregnating n-eicosane into APDWs under vacuum. The APDWs well-preserved the unique anisotropic porous structure and effectively prevented the liquid leakage issues of n-eicosane. Differential scanning calorimetry (DSC) analysis indicated that ADPCMs possessed an extremely high thermal storage density (202.9–213.5 J/g). The introduction of polydopamine (PDA) effectively increased the photothermal conversion and storage efficiency (up to 90.5%) of ADPCMs. Moreover, with the increasing content of phytic acid (PA) in the composites, the peak heat release rate (pHRR) and total heat release (THR) of ADPCMs decreased significantly, revealing the improved flame retardancy of ADPCMs. Biosourced functional composites show considerable potential for application in solar utilization systems.