Underwater Oleophobic Electrospun Membrane with Spindle-Knotted Structured Fibers for Oil-in-Water Emulsion Separation

The potential of spider silk as an intriguing biological prototype for collecting water from a humid environment has attracted wide attention, and various materials with suitable structures have been engineered. Here, inspired by this phenomenon, a kind of superwetting poly(vinylidene fluoride) (PVDF) membrane with spindle-knotted structured fibers was prepared by the electrospinning method followed by oxygen plasma etching treatment. The prepared membrane presented a satisfactory separation efficiency for various oil-in-water emulsions. The cooperative effect of the special wettability property and the spindle-knot structure stimulated the emulsified oil droplets to accumulate quickly on the membrane surface. A model that explains the accumulation of emulsified oil droplets has also been developed. Furthermore, an artificial fiber comprising a micron-sized spindle-knot structure was prepared by the dip coating method to clearly illustrate the aggregation process of the emulsified oil droplets and to verify the theoretical explanation. We hope that this study will provide new inspiration for oil/water emulsion separation techniques.

Automated summary

Inspired by spider silk's ability to collect water from a humid environment, a superwetting poly(vinylidene fluoride) (PVDF) membrane with spindle-knotted structured fibers was prepared using the electrospinning method followed by oxygen plasma etching treatment. The membrane showed excellent separation efficiency for various oil-in-water emulsions, as the combination of special wettability property and spindle-knot structure facilitated quick accumulation of the emulsified oil droplets on the membrane surface. A model explaining this accumulation was developed and verified using an artificial fiber with micron-sized spindle-knot structure.