All‐Biomass Tough Aerogel Fiber for Super Thermal Insulating Textile

Nowadays, the development of all‐biomass aerogel fibers that integrate robust mechanical properties with superior thermal insulation remains a significant challenge. In this study, all‐biomass core‐shell structural aerogel fiber with the cellulose acetate shell and the silk fibroin core was developed to address these issues. The resulting cellulose acetate‐silk fibroin aerogel fiber demonstrated impressive mechanical properties, with the stress and strain at break of 28.18 MPa and 104%, respectively. These properties are attributed to lithium chloride‐induced slow molding and heat treatment‐derived crystallization enhancement. Furthermore, the cellulose acetate‐silk fibroin aerogel fiber possessed excellent water resistance and easy dyeability. Notably, based on the multilevel porous structure, low thermal conductivity, and core‐shell structure of aerogel fiber, the knitted fabric exhibited outstanding thermal insulation performance, such as a |Δ T | of 60.6 at hot stage temperature of 120 °C, outperforming previous studies. Consistent with the experimental findings, the numerical simulation results revealed that the exceptional performance could be attributed to the macro‐/nano‐sized pores in the cellulose acetate shell capturing stationary air for suppressing thermal conduction/convection, and walls in the silk fibroin core enhancing infrared reflectance for preventing thermal radiation. This innovative approach paves the way for designing sustainable aerogel fiber and multifunctional textiles, with promising applications in personal thermal management.