Silicified Wood‐Inspired, High‐Strength Fire‐Resistant Chitin‐Based Aerogels for Sustainable High‐Temperature Thermal Insulation

ABSTRACT Biobased aerogels show great potential to replace traditional petrochemical‐based thermal insulation materials due to their sustainability and comparable physical properties. Unfortunately, their insufficient compressive strength (often < 0.5 MPa) and high flammability limit their practical applications. To bridge this gap, we here report a bottom‐up biomimetic mineralization strategy to prepare biobased aerogel (SiB@CC) by impregnating chitin/chitosan aerogels with sodium silicate and borax, followed by freeze‐drying and thermal cross‐linking. The SiB@CC aerogels exhibit high compressive strength (up to 2.25 MPa) and exceptional energy absorption. The aerogel can withstand 81 000 times of its own weight without failure, and its energy absorption efficiency is superior to that of most polymers, metals, and ceramics. Benefiting from the ability to form a robust organic‐inorganic char layer, the SiB@CC aerogels exhibit excellent fire resistance and cannot be ignited, with a limiting oxygen index value exceeding 90%. Moreover, the aerogel shows exceptionally high‐temperature thermal insulation, as evidenced by a backside temperature of only 130 ° C after 600 s continuous exposure to ∼1300 ° C flame. This work offers a promising biomimetic approach for preparing bio‐based aerogels combining high‐strength, fire‐resistant, and super thermal insulation, which is expected to find great potential for sustainable high‐temperature thermal insulation.