Amphiphobic Nanofibrous Silica Mats with Flexible and High-Heat-Resistant Properties

In this study, for the first time, we fabricated flexible, high-heat-resistant, and amphiphobic mats by (fluoroalkyl)silane (FAS) modification of electrospun pure silica nanofibrous mats. The inorganic silica nanofibrous mats were obtained via electrospinning the blend solutions of poly(vinyl alcohol) (PVA) and silica gel, followed by calcination to remove the organic component. The PVA/silica and silica fibers were found to be randomly oriented as nonwoven mats with fiber diameters in the range of 150−500 nm. After the FAS modification, the surface wettability of the silica mats was converted from amphiphilic to amphiphobic. The fluorinated mat with the bead-on-string structure showed the highest water contact angle (WCA) of 154° and oil contact angle (OCA) of 144°. Additionally, the fluorinated inorganic fibrous mats exhibited a high heat resistance; they kept their hydrophobicity (WCA of 138°) and oleophobicity (OCA of 132°) even after the annealing treatment at 450 °C for 30 min. Potential applications of the fluorinated fibrous mats include high-temperature filtration, selective filtration, and self-cleaning coatings.