Ambient-Pressure-Dried Biomass Aerogel toward Robust Cross-Linked Networks and Exceptional Mechanical Performances during Combustion

Biomass aerogels are poised as compelling thermal insulators but are seriously plagued by energy-intensive preparation processes, mechanical strength degradation, and structural collapse under thermal shock. In this study, we present a simple and eco-friendly atmospheric drying method and an in situ carbonization strategy for fabricating biomass aerogels with high strength, both at room temperature and in fire scenarios. The air bubbles, trapped by biomass with a thermoreversible gelling ability, such as gellan gum, serve as pore templates for the direct preparation of biomass aerogels in mild conditions without using organic solvents. The intricate physicochemical cross-linking networks result in an ultrahigh compression modulus of 40.8 MPa under normal conditions. In particular, this organic aerogel spontaneously transformed into highly cross-linked polyaromatic structures with a high modulus of >18 MPa upon exposure to high temperatures or fire. What is more, the unique in situ carbonization ability enables aerogels to provide fire resistance (LOI value of 31.5%), high strength support, and excellent thermal insulation under combustion. This study provides new insights into endowing the biomass aerogel with exceptional mechanical properties under extreme conditions and offers a green strategy to achieve in situ preparations of aerogels with high performance.