Ultralight, hydrophobic, monolithic konjac glucomannan-silica composite aerogel with thermal insulation and mechanical properties

Konjac glucomannan (KGM) aerogel was prepared by a facile freeze-drying process, which was used as green sustainable biopolymer matrix to synthesis three-dimensional (3D) network interpenetrated KGM-SiO2 aerogel with thermal insulation performance and high mechanical properties. Herein, we explored that the potential structure-performance relationship of KGM aerogel between the physical parameters, morphology and thermal insulation. Besides, the preparation conditions of KGM aerogel including concentration of KGM, Na2CO3-to-KGM mass ratio were investigated. Meanwhile, the KGM aerogel and KGM-SiO2 aerogel were characterized using scanning electron microscopy, Fourier transform infrared spectrometer, Brunauer-Emmett-Teller method, thermogravimetric analysis and contact angle test. Results showed that the as-prepared KGM aerogel exhibited excellent thermal insulation performance (λ = 0.021 W m-1 K-1) and low bulk density (ρ = 0.030 g cm-3) when concentration of KGM was 2 wt% and Na2CO3-to-KGM mass ratio of 0.12. In order to improve the mechanical properties and high hydrophobicity of biopolymer aerogel, a novel of KGM-SiO2 aerogel was successful fabricated by incorporating methylsilsesquioxane (MTES) derived SiO2 into the KGM matrix via the freeze-drying method. The obtained aerogel exhibited remarkable compressive strength (δmax = 1.65 MPa at 80% strain), high specific surface area of 416.1 m2 g-1, high hydrophobicity (θ = 146° for water) and low thermal conductivity of 0.032-0.039 W m-1 K-1. Thus, the high-performance KGM-SiO2 aerogel would be further expand the thermal insulation application in sustainable development and energy-saving building.