Superior hydrophobicity of nano-SiO2 porous thermal insulating material treated by oil-in-water microemulsion

• Published in: Ceramics international Vol. 48; no. 7; pp. 9450 - 9458
• Main Authors: Song, Xiaolong, Fu, Renli, Liu, Houbao, Huang, Zeya, Su, Xinqing, Liu, Xuhai
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2022
• Subjects: Hydrophobicity; Nano-SiO2; Porous; Thermal insulation; Hydrophobicity; Nano-SiO2; Thermal insulation; Porous
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2021.12.142

Nano-SiO2 porous thermal insulating material (TIM) has drawn tremendous research interests due to its advantages of low density, high porosity and low thermal conductivity. However, its long-term stability in humid environment can be severely deteriorated by the high hydrophilicity resulting from tetrahedral coordination of oxygen and capillary effect of porous structure. It is still a great challenge to cost-effectively fabricate bulk TIM with superior hydrophobicity and consequent remarkable self-cleaning capability. Herein, via an oil-in-water microemulsion treatment, we have proposed a new strategy to construct 3D superior hydrophobic nano-SiO2 porous TIM. The polymethylhydrosiloxane-modified TIM exhibits a large water contact angle of 166°, and corresponding excellent self-cleaning characteristic while maintaining low thermal conductivity of 0.031 W/m·K. Moreover, our high hydrophobicity of TIM exhibits excellent durability under high temperature up to 400 °C, high humidity of 100%, and chemical erosions. Detailed knowledge of the physical chemistry basis of the superior hydrophobic nano-SiO2 porous TIM can provide great opportunity to fabricate advanced self-cleaning and heat insulating devices especially targeted for harsh environments.