Hydrophilic polyacrylonitrile nanofibrous membranes via Ritter reaction: Preparation, characterization and antibacterial properties (N-halamine)

Electrospun (e-spun) nanofiber materials have emerged as a prominent research focus owing to their extensive and promising potential applications across biomedical, energy, and environmental domains. Polyacrylonitrile (PAN) is a commonly used polymer for electrospinning (e-spinning). Due to insufficient hydrophilic properties of nitrile groups of PAN, its e-spun nonwoven membranes had low water absorption and moisture absorption, which limited application in medical and health fields. In this study, it was investigated that the hydrophilic modification of e-spun PAN nanofiber membrane (NFM) was conducted via Ritter reaction to convert nitrile groups into hydrophilic amide ones, thereby improving the hydrophilicity of PAN NFMs. The surface morphologies and structure of the modified e-spun fibers were characterized and verified by SEM, FTIR and XPS. After 60-90 min of Ritter reaction, the fiber diameter of the PAN NFM became thicker, transforming from a hydrophobic membrane to a hydrophilic one, and the water contact angle decreased from 124.2 to 40.7 degrees. The amidated PAN obtained membrane was post-treatment with sodium hypochlorite to make some amide groups change to N-halamine, which took the PAN NFM antibacterial activity or bacteriostasis. This work suggested a strategy that the espun PAN NFMs modified would have a promising application in medical dressings, air filtration, etc.