Transparent, Superflexible Doubly Cross-Linked Polyvinylpolymethylsiloxane Aerogel Superinsulators via Ambient Pressure Drying

Abstract

Aerogels have many attractive properties but are usually costly and too friable, which always limit their practical applications. Besides, almost all of the reinforced aerogels sacrifice the transparency or superinsulating properties. Here we report unprecedented superflexible polyvinylpolymethylsiloxane ((CH2CH)n(CH3)SiO2/2) aerogels that are facilely prepared from a single precursor vinylmethyldimethoxysilane or vinylmethyldiethoxysilane without organic crosslinkers. It is based on a consecution of radical polymerization and hydrolytic polycondensation followed by ultralow-cost, highly scalable ambient pressure drying directly from alcohol as a drying medium without any modification and additional solvent exchange. The resulting aerogels and xerogels show a unique, homogeneous, tunable, highly porous, doubly crosslinked nanostructure with the elastic polymethylsiloxane network crosslinked with flexible hydrocarbon chains. An outstanding combination of ultralow cost, high scalability, uniform pore size, high surface area, high transparency, high hydrophobicity, excellent machinability, superflexibility in compression, superflexibility in bending and superinsulating properties has been achieved in a single aerogel and xerogel for the first time. This study represents a significant progress of porous materials and makes the practical applications of transparent flexible aerogel-based superinsulators realistic.