Improved mechanical properties and hydrophilicity of electrospun nanofiber membranes for filtration applications by dopamine modification

Electrospun nanofiber membranes (ENMs) are an emerging platform for membrane filtration; however, widespread applications of ENMs are hindered by poor mechanical strength attributed to their high porosity, intrinsically low, random fiber orientations and weak interactions between fiber junctions. In addition to suitable mechanical properties, most water-based filtration processes require membranes to be hydrophilic in order to resist fouling and enhance water flow. In this study, we demonstrate a simple chemical modification capable of improving the mechanical properties of polyacylonitrile (PAN) and polysulfone (PSu) ENMs. The chemical modification involves the polydopamine (PDA), a hydrophilic polymer. PDA has the dual benefit of hydrophilization and strengthening of ENMs to improve their wettability and tolerance to operational and handling conditions. When deposited onto the fibers, PDA promotes bonding between fibers by coating junction points throughout the nonwoven. The coated nonwoven membranes showed a 100 to 300% increases in tensile strength and Young׳s Modulus with no decrease in flexibility while retaining their porous structure and high water permeability. For hydrophobic PSu ENMs, the hydrophilicity was also significantly improved after coating. •The weakness of nanofibers is a key obstacle toward their use in liquid filtration.•Enhancing fiber–fiber bonding is essential to increase strength.•Polydopamine was coated onto the nonwovens to glue fiber junctions together.•Modified polysulfone and polyacrylonitrile nanofibers exhibit improved strength.•Polydopamine modification enhances hydrophilicity of hydrophobic nanofibers.