Surface modification for enhanced Anti-Wetting properties of electrospun omniphobic membranes in membrane distillation

Membrane wetting caused by substances in the feed solution with low surface tension has posed serious issues for membrane distillation (MD). Omniphobic membranes could be helpful when dealing with this problem because they strongly repel liquids with a wide range of surface tensions. We fabricated electrospun omniphobic membranes containing PVDF-TEOS-PFDTMS, PVDF-HFP-TMOS-PFDTMS, and PVDF-HFP-TEOS-PFDTMS. All electrospun membranes have shown contact angles >90 degrees, but the electrospun membrane containing PVDF-HFP-TEOS-PFDTMS has shown super repellence with a contact angle >150 degrees and maintains stable salt rejection and water flux in direct contact MD processes in the presence of sodium dodecyl sulfate surfactant (up to 0.3 mM). Furthermore, the morphology and crystallinity of the electrospun membranes were studied by scanning electron microscopy and Fourier-transform infrared spectroscopy, and the percentage composition of elements was analyzed by x-ray photoelectron spectroscopy. liquid entry pressure, mechanical strength, and the porosity of the electrospun omniphobic membranes were also studied.