Fluorocarbon-Based Selective-Superwetting Nanofibrous Membranes with Ultraviolet-Driven Switchable Wettability for Oil–Water Separation

Selective-superwetting membranes possess controllable wettability and have great potential in the oil–water (OW) separation field. The electrospinning technique has advantages in fabricating nanofibrous materials with distinguishing features such as high porosity and large surface area. However, in recent years, there have been a few studies on preparing photoinduced superwetting membranes by electrospinning. In this study, an ultraviolet-driven selective-superwetting nanofibrous membrane was prepared by electrospinning poly(vinylidene fluoride)-cohexafluoropropylene (PVDF-HFP) blended with fluorinated TiO2 nanoparticles. The wetting behavior of the membrane can be tuned between superhydrophobic/superoleophilic and superhydrophilic/underwater superoleophobic by two processes, ultraviolet (UV) irradiation, and heating, during which the water contact angle (WCA) fluctuates rapidly from 170 to 0° and back to 160°. The reliability of the controllable wettability was proven by a 15-cycle conversion test, and the nanofibrous membrane remained superhydrophobic thereafter. Our results have promising multipurpose applications as an effective and flexible solution to more complex oil–water mixtures in wastewater abatement.