Transparent, ultraflexible, and superinsulating nanofibrous biocomposite aerogels via ambient pressure drying

Abstract

Aerogels are attractive porous materials but are usually optically opaque and mechanically brittle and their drying process is usually energy consuming, which limit their practical applications. Preparation of transparent and flexible aerogels via ambient pressure drying (APD) remains a challenge. Herein we report unprecedented optically transparent, mechanically flexible, and thermally superinsulating nanofibrous biocomposite aerogels based on 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized starch (TOS) and polyorganosiloxane via facile APD without any modification. The aerogels combine good transparency, high surface area, high hydrophobicity, superflexibility, excellent machinability, thermal superinsulation, and high environmental stability. These merits are achieved by the three-dimensional, homogeneous, highly porous, methyl group-rich, and nanofibrous structure composed of flexible TOS and elastic polyorganosiloxanes with nanoscale pores and fibers. In addition, a biocomposite aerogel-based flexible solar thermal receiver that can effectively convert sunlight into useful heat is demonstrated. This work provides a green, versatile, and powerful strategy for preparing transparent flexible porous materials and will significantly contribute to the practical applications of aerogels in thermal/optical regulation and saving energy, such as thermal superinsulation for transparent windows, solar thermal receivers, and electronics.