Nanoparticle decorated fibrous silica membranes exhibiting biomimetic superhydrophobicity and highly flexible properties

Inspired by the self-cleaning lotus leaf, here we report the fabrication of flexible fluorinated silica nanofibrous membranes with biomimetic non-wettable surfaces by electrospinning blend solutions of poly(vinyl alcohol) (PVA) and silica gel in the presence of silica nanoparticles, followed by calcination and fluoroalkylsilane (FAS) modification. The resultant silica nanofibers exhibited a lotus-leaf-like structure with numerous nanoparticles decorated on the fiber surfaces due to the rapid phase separation in electrospinning and calcination processing. The content of silica nanoparticles incorporated into the fibers proved to be the key factor affecting the fiber surface morphology and wettability. The fluorinated silica fibrous membranes containing 38.8 wt% silica nanoparticle showed the highest water contact angle (WCA) of 155°, oil contact angle (OCA) of 143°, orange juice contact angle (OJCA) of 142°, and milk contact angle (MCA) of 137°. Additionally, the fluorinated silica membranes exhibited good flexibility and the flexibility was also characterized by KES-FB2S. We believe that this new class of inorganic membranes is particularly promising for the development of high-temperature filtration, novel easy-clean coatings, and even flexible electronics.