Flexible, elastic, and superhydrophobic silica-polymer composite aerogels by high internal phase emulsion process

Abstract Flexible, elastic, low density, superhydrophobic, and low thermal conductive silica-polymer composite aerogel materials were prepared by a high internal phase emulsion (HIPE) process followed with sol-gel process. Flexible silica aerogels were grown in the scaffold of macro-porous flexible polymer monolith to overcome the brittle nature of silica aerogels. Initially, porous polymer monolith was prepared by HIPE and was used as a scaffold for preparation of flexible silica aerogels by sol-gel process followed by supercritical drying. Polymer monolith was soaked in a pre-hydrolyzed methyltrimethoxysilane (MTMS) based silica sol and gelation was achieved by two step sol-gel process. Composite monolith possess extreme properties such as high flexibility, elasticity, superhydrophobicity (165°), low density (0.045 g/cm3) and thermal conductivity (0.040 W/m·K). This novel way of preparation allows us to overcome the fragile nature of MTMS based flexible silica aerogels while maintaining textural, physical, and functional properties. Hence such materials are highly useful for corrosion resistant thermal insulation in various fields.