Poly(vinyl alcohol) aerogels based on amino modified boron nitride nanosheets and phosphorus containing PEG for shape-stable phase change composites with enhanced thermal conductivity and flame-retardant properties

Phase change materials (PCMs) are highly regarded for their chemical stability and thermal energy storage capacity, making them ideal for energy storage and temperature management. To overcome the flammability limitation of traditional PCMs, polyethylene glycol (PEG) was phosphorus modified, and worked as an acid source when the material exposure to fire. Polyvinyl alcohol (PVA) was employed as a supporting matrix, and boron nitride nanosheets functionalized with amino groups (BN-NH2) were introduced to enhance thermal conductivity. Through vacuum impregnation of phosphorus containing PEG (P-PEG), a flame-retardant and leakage-proof PVA/BN-NHS aerogel/PEG composite phase change material was successfully prepared. The results showed that the PVA/BN-NHS aerogel exhibited an impressive P-PEG loading capacity (1843 %) and significant shape stability, owing to the high aspect ratio of the PVA aerogel and strong interfacial interactions between PPEG molecules and PVA. The inclusion of high thermal conductivity BN-NHS nanosheets improved the composite material's thermal conductivity to 0.34 W/(m & sdot;K), which is approximately 40 % higher than that of P-PEG alone. Additionally, the composite phase change material exhibited a high latent heat of fusion (132.09 J/g) and an encapsulation efficiency of up to 99.89 %. The presence of P-PEG and BN-NHS significantly promoted carbon formation, enhancing the PCM's flame retardancy, as evidenced by an 84.7 % reduction in peak heat release rate and a 62.82 % reduction in total heat release. The proposed system combines the thermal insulation properties of aerogels with the heat storage and temperature regulation functions of phase change materials, effectively reducing the flammability of organic PCMs, and demonstrating promising application prospects in thermal insulation.