Rigid and Fire-Resistant All-Biomass Aerogels

Improving the mechanical properties and fire resistance at the same time has become a tough challenge in the study of high-performance biomass foamlike materials. To tackle this dilemma, fully biomass-based aerogels based on renewable porcine gelatin (PG) and phytic acid sodium salt (PA) were designed through a green freeze-drying method. Owing to the low flammability and the strong interaction of these two compounds, the resulting aerogels exhibited both high fire resistance and extra-strong strength, offering a novel solution to the aforementioned difficulty. Benefitting from the design of the strong physical cross-linking structure of PG, PA, and clay, the compressive modulus value of the aerogel was as high as 25.1 MPa, nearly 180 times that of the poly(vinyl alcohol) control. These biobased aerogels exhibited extremely low flammability and superior smoke suppression, that is, the limiting oxygen index values of the aerogel were as high as 50.1%, and the total smoke release decreased from 213 to 13.5 m2 in comparison with those of commercial PU foam. All the results indicated that green aerogels with excellent combination properties will be promising in the future.