Bio-based chitosan aerogel composites with multifunctional combination of thermal insulation, sound absorption, flame retardancy, and superhydrophobicity

Bio-based chitosan aerogels for thermal insulators are greatly concerned in green low-carbon buildings field owing to their low thermal conductivity and low environmental load. However, chitosan aerogels are severely restricted by multifunctional integration failure of thermal/acoustic insulation, flame retardancy and superhydrophobicity. Herein we report on bio-based chitosan aerogel composites with multifunctional combination, realized by hybriding fumed silica and introducing glass fiber preform in formation of chitosan networking skeletons. Such bio-based chitosan aerogel composites indicate the first implement of near net forming due to the evidence of almost near-zero shrinkage compared with conventional huge-shrinkage chitosan-nature aerogels. The aerogel composites achieve thermal conductivity of 21 mW m −1 K −1 , noise reduction coefficient of 0.70, limiting oxygen index of 57.5%, and water contact angle of 151° (moisture absorption rate of 0.48% for 160 h at 70 °C and 85% relative humidity). Importantly, we design a series of container building model simulation devices for validating thermal insulation and thermal safety in the condition of chitosan aerogel composites layer embed inside modules case. The resultant evidence shows the superior thermal insulating feature despite experiencing the extreme housing temperatures of −43 or 49 °C, simultaneously retaining the safety situation (smokeless, non-charring appeared at inner wall) even facing the flame attack of ∼1200 °C. Besides, durability for thermal insulation and tensile strength of chitosan aerogel composites both present an outstanding stability at extreme temperatures or physically punctured damage. The combination of thermal/acoustic insulation, flame retardancy and superhydrophobicity makes this aerogel composite very promising for thermal insulators in energy-saving buildings.