From Gels to 3-D Networks: Creating Multifunctional Polymer-silica Nanofiber based Aerogels

Gels containing water or solvents abound in applications with considerable efforts being made to fabricate new ones with enhanced functionalities. An area that remains less explored is the creation of aerogels by replacing the liquid matrix of gels with air. Can we preserve the structure of these systems on liquid removal and can we create materials that are just as versatile by doing so? We present a facile and sustainable solid templating approach to fabricate highly porous, flexible aerogels of hybride nanofibers of cellulose acetate and silica which are produced via sol gel electrospinning. SEM micrographs demonstrate a hierarchical architecture consisting of large secondary pores (30-50 μm) interconnected by a network of entangled nanofibers with 2-5 μm primary pores. XPS and in-situ FTIR studies provide evidence that thermal treatment of as-prepared aerogels results in crosslinking the silica-CDA network therefore enhancing their mechanical stability and hydrophobicity without compromising their low bulk density (~10 mg.cm^-3) and porosity (>98%). Thermal studies demonstrate highly enhanced thermal stability and flame retardancy. These functional features together with ease of processing make these aerogels just as promising, if not more, than their liquid-based analogs!