Surface modification of polyacrylonitrile nanofibrous membranes with superior antibacterial and easy-cleaning properties through hydrophilic flexible spacers

Surface modification which creates surfaces capable of killing adherent bacteria and simply repelling dead bacteria was performed on electrospun polyacrylonitrile (PAN) nanofibrous membranes. Briefly, nitrile groups on the PAN nanofiber surfaces were reduced into amino groups, extended tethers by coupling of hydrophilic flexible spacers, followed by reaction with polyhexamethylene guanidine hydrochloride (PHGH) to provide antibacterial properties. The surface morphology and chemical composition of the functionalized nanofibrous membrane were characterized by scanning electron microscopy (SEM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FT-IR) and energy-dispersive spectroscopy (EDS). Furthermore, the antibacterial activities of the PHGH-immobilized nanofibrous membranes were assayed with Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). It was found that these PHGH-immobilized nanofibrous membranes possessed highly effective antibacterial activities which were highly retained even after three cycles of antibacterial assays. The functionalized membranes also exhibited significantly enhanced easy-cleaning performance due to the incorporation of hydrophilic spacers. Water permeance results illustrated that the novel modified PAN nanofibrous membranes showed potential in the applications of water filtration.