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

Abstract

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.