Electro-spinning/netting (ESN) as a cutting-edge technique evokes much interest because of its ability in the one-step preparation of versatile nano-fiber/net (NFN) membranes. Here, a controllable fabrication of polyurethane (PU) NFN membranes with attractive structures, consisting of common electrospun nanofibers and two-dimensional (2D) soap bubble-like structured nano-nets via an ESN process is reported. The unique nanoscaled NFN architecture can be finely controlled by regulating the solution properties and several ESN process parameters. The versatile PU nano-nets comprising interlinked nanowires with ultrathin diameters (5-40 nm) mean that the NFN structured membranes possess several excellent characteristics, such as an extremely large specific surface area, high porosity and large stacking density, which would be particularly useful for applications in ultrafiltration, special protective clothing, ultrasensitive sensors, catalyst support and so on.

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 155u, oil contact angle (OCA) of 143u, orange juice contact angle (OJCA) of 142u, and milk contact angle (MCA) of 137u. 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.

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