Efficient thermal insulation through all-biomass silk fibroin composite aerogel 3D-reinforced by natural down-fiber

Biomass-based aerogels offer numerous individual benefits in thermal insulation applications. However, their generally weak mechanical properties impair the further development of aerogels. Herein, natural down-fiber (DF) reinforced silk fibroin (SF) all-biomass aerogel was rationally designed. The developed 3D-reinforcement structure, in which DF was physically interspersed in SF in multiple directions and hydrogen bonds formed between DF and SF, resulted in significantly enhanced compression stress of 146.3 kPa (3.44 times greater than that of SF aerogel, which attained 42.57 kPa) and impressive compression resilience. Meanwhile, the DF@SF aerogel displayed a hierarchical porous structure (97.64 % porosity) with micron-sized holes and nano-sized pores, as well as low thermal conductivity of 0.034 W m-1 K-1, which would effectively inhibit air circula-tion and limit heat transfer for improved thermal insulation. Moreover, the addition of DF reduced the average hole diameter, which further prevented heat convection and minimized heat radiation inside the aerogel. As a result, the DF@SF aerogel demonstrated excellent thermal insulation performance with a wide range of working temperatures from-40 to 160 degrees C and stability for recyclable usage. Therefore, this all-biomass DF@SF aerogel could offer an alternative form of high-performance thermal insulation. This strategy will also inspire more research into the construction of 3D-reinforced functional aerogels and their applications in thermal insulation, sound insulation, biomedicine, and other related areas.