Facile fabrication of bio-based PAG-modified chitosan aerogels for enhanced thermal insulation and flame-retardant performance

The growing issues of environmental pollution and energy consumption have spurred extensive research into the development of renewable heat-insulation materials. This study proposes a facile and cost-effective strategy to fabricate biodegradable chitosan(CS) aerogels by incorporating a phosphorus-based flame retardant (PAG), which was synthesized through the esterification of biomass-derived phytic acid and mannitol. Experimental results shows that the composite aerogels CS-PAG exhibit intrinsic flame-retardant performance, outstanding thermal insulation and mechanical properties. Compared to pure CS aerogels, the thermal conductivity of CS-PAG decreased to 0.0307 W/(m·K), while the compressive modulus increased to 697.41 kPa. This improvement is attributed to an optimized porous network formed by covalent and hydrogen bonding interactions between PA and CS. Remarkably, the modified aerogels exhibited a limited oxygen index of 41.1 % and achieved the V-0 rating in the UL-94 vertical burning test. Meanwhile, the total heat release and the peak heat release rate values were significantly reduced by 24.9 % and 58.2 %, respectively. The bio-based chitosan aerogel, endowed with superior flame-retardant properties, demonstrates significant potential as an innovative and sustainable material for thermal insulation applications.