Formation of Hydrophobic and Superhydrophobic Coatings on Track-Etched Membrane Surfaces to Create Composite Membranes for Water Desalination

Different methods have been considered for the formation of coatings on the surface of a hydrophilic poly(ethylene terephthalate) track-etched membrane with the help of electron-beam dispersion of polymers in vacuum. It has been shown that, when ultrahigh-molecular-weight polyethylene and polypropylene are used as targets for the dispersion, this method makes it possible to obtain hydrophobic and highly hydrophobic coatings with a morphologically developed structure on the membrane surface. The deposition of a thin polytetrafluoroethylene layer on their surfaces via electron-beam dispersion has resulted in the formation of a superhydrophobic coating. A one-layer superhydrophobic coating has been formed on the membrane surface with the use polytetrafluoroethylene as a target. The morphology and structure of the surfaces of the obtained composite membranes have been studied by atomic force and scanning electron microscopies. The chemical composition of the polymer coatings deposited onto the track-etched membrane surface has been studied by X-ray photoelectron spectroscopy. It has been shown that the elaborated composite membranes can be used for desalinating an aqueous sodium chloride solution by membrane distillation. It has been revealed that the use of the thin hydrophobic layer in combination with the thick hydrophilic substrate increases the productivity of the membrane distillation process.