Synthesis of flexible aerogel composites reinforced with electrospun nanofibers and microparticles for thermal insulation

Abstract

Flexible silica aerogel composites in intact monolith of 12 cm were successfully fabricated by reinforcing SiO2 aerogel with electrospun polyvinylidene fluoride (PVDF) webs via electrospinning and sol-gel processing. Three electrospun PVDF webs with different microstructures (e.g., nanofibers, microparticles, and combined nanofibers and microparticles) were fabricated by regulating electrospinning parameters. The as-electrospun PVDF webs with various microstructures were impregnated into the silica sol to synthesize the PVDF/SiO2 composites followed by solvent exchange, surface modification, and drying at ambient atmosphere. The morphologies of the PVDF/SiO2 aerogel composites were characterized and the thermal and mechanical properties were measured. The effects of electrospun PVDF on the thermal and mechanical properties of the aerogel composites were evaluated. The aerogel composites reinforced with electrospun PVDF nanofibers showed intact monolith, improved strength, and perfect flexibility and hydrophobicity. Moreover, the aerogel composites reinforced with the electrospun PVDF nanofibers had the lowest thermal conductivity (0.028 W·m -1·K-1). It indicates that the electrospun PVDF nanofibers could greatly improve the mechanical strength and flexibility of the SiO2 aerogels while maintaining a lower thermal conductivity, which provides increasing potential for thermal insulation applications. © 2013 Huijun Wu et al.