Mechanically robust, thermally insulating and photo-responsive aerogels designed from sol-gel electrospun PVP-TiO2 nanofibers

We present a robust approach for fabricating polyvinylpyrrolidone (PVP)-titania (TiO2) nanofibrous aerogels (NFA) with multifunctional and triggered performances. These low density (∼ 10 mg cm−3) 3D self-supported aerogels having an intrinsically lamellar porous structure (> 99% porosity) are created via solid templating of sol-gel electrospun PVP-TiO2 hybrid nanofibers. The photocatalytic activity of TiO2 allows for on-demand application wherein the aerogel exhibits antibacterial properties upon UV exposure to bacteria such as Escherichia coli and Salmonella enterica. Significantly, while the aerogel sorbs common volatile organic components (VOCs) or oil due to its innate porosity, exposure of the aerogel to ultraviolet (UV) radiation leads to their decomposition. The PVP-TiO2 NFA exhibits a low thermal conductivity (0.062 W m−1 K−1) together with considerable mechanical flexibility up to strains of 50% with >90% recovery, without the need for post-processing. The photo-responsive attributes combined with mechanical resilience, oleophilicity and thermal insulation properties render these aerogels viable candidates for a diverse range of applications. We discuss such property enhancements in terms of the interaction between PVP and TiO2 and aerogel microstructure.