Monolithic mullite aerogels via an organic-inorganic hybridization strategy enabled by chitosan: Structure and thermal properties

The organic-inorganic hybridization has emerged as a promising strategy in advanced materials research. Herein, chitosan, a bio-polymer, was successfully introduced to fabricate monolithic mullite aerogel with excellent performance under ambient pressure drying (APD). The structures and properties of the aerogels were carefully regulated by varying the chitosan concentrations and acid concentrations, and the aerogels were characterized by SEM, FTIR, XPS, NMR, TG/DTG, BET, XRD, and so on. The results confirmed the formation of organic-inorganic hybrid network through coordination bond and hydrogen bonding, conducive to APD. The aerogels possess low density (0.225–0.292 g/cm 3 ), low thermal conductivity coefficient (0.03037–0.04101 W·m −1 ·K −1 ), low mass loss (25.90–34.32%), and high specific area (442.39–748.26 m 2 /g). Furthermore, an excellent high-temperature stability was granted owing to the superior dimensional stability and pore structural preservation of the aerogel under thermal cycling experiments. After heat treatment at 800–1400 °C, the aerogel reached high compressive strength of 0.29–4.82 MPa. This paper provides a facile preparation of high-performance aerogels, offering possibilities to confront harsh operating environments.