Monolithic chitosan-silica composite aerogel with comprehensive performances prepared by SBG-FD method

Silica aerogels are viewed as potential thermal insulation materials because they are highly porous, adiabatic and lightweight. The lack of mechanical strength and hygroscopicity are the main barriers to their application. In order to tackle these issues, a direct sol-blending-gel combing freezing drying (SBG-FD) technique is used to create trimethylchlorosilane (TMCS)-modified natural polysaccharide-reinforced chitosan-silica aerogel (CS-T-SA) in this work. This brand-new CS-T-SA possesses three-dimensional network structure, and its thermal conductivity reaches 0.0360 W m−1 k−1 at 30 °C with bulk density as low as 0.0485 g cm−3 and volume shrinkage to a minimum of 5%. Hydrophobic modification with TMCS gives the composite aerogel a promisingly high hydrophobicity with the water contact angle of 135.1°. In comparison to conventional silica aerogels, the chitosan-silica aerogels exhibit improved mechanical characteristics, with no brittle rupture up to at least 80% strain and stress at 80% strain values of 0.285–0.486 MPa. Remarkably, aerogel monoliths can be machined and sculpted using tools. This demonstration to produce monolithic and machinable, mesoporous aerogels with low-density from bio-sourced, renewable and nontoxic precursors, combined with good thermal stability and hydrophobicity opens up new possibilities for biopolymer-silica aerogel applications and represents a significant approach toward the commercialization of biopolymer-silica aerogels.