Facile fabrication of hydrophobic polyvinylpolysilsesquioxane aerogels with improved optical properties

Abstract

Optically transparent and mechanically enhanced aerogels are promising nanoscale materials for thermally insulating window glazing. However, there still exists a longstanding challenge for silica aerogels to realize the combination of optical and mechanical properties. Here, we present a facile synthetic means towards hydrophobic polyvinylpolysilsesquioxane (PVPSQ) aerogels with improved optical properties, originating from polyvinyltrimethoxysilane polymers in ethanol−water medium. The as-prepared PVPSQ aerogels with surface hydrophobicity modification show high water contact angle of 124 ± 5°. Benefiting from the homogenous networks acquired in the ethanol−water solvent, hydrophobic PVPSQ aerogels have a huge surface area of 1106 ± 50 m2/g and a high visible-light transmittance of 92.3% at 550 nm wavelength. Moreover, monolithic PVPSQ aerogels with doubly cross-linked nanostructure exhibit excellent mechanical property and thermally insulating capacity. The compressive strength with 20% strain is 0.71 MPa, and the thermal conductivity of typical sample is 0.0271 W/(m·K) in ambient environments. All these results will be meaningful for the design and industrial production of transparent insulating materials.