Electrochemical wet-spinning process for fabricating strong PAN fibers via an in situ induced plasticizing effect

This work reports a novel design strategy for a strong polyacrylonitrile (PAN) fiber using an electrochemical wet-spinning process. First, a spinning dope was prepared using PAN copolymer containing methyl acrylate. This was spun using a conventional wet-spinning setup, but with a special nozzle spinneret whereby an electric potential could be applied. In situ electrochemical oxidation of methyl acrylate was then induced within the nozzle, resulting in electrochemical demethylation of the PAN copolymer. The subsequently endowed hydrophilic and hygroscopic properties of the PAN fibers improved the chain mobility of the PAN molecules and reduced void formation during wet-spinning. Investigation of the quantitative relationships between the degree of electrochemical demethylation and the mechanical properties of the PAN fibers clarified the in situ plasticization effect of absorbed water induced by the electrochemical demethylation. The Young's modulus and tensile strength of the PAN fibers were improved by 23.4% and 23.5%, respectively, and the breaking strain was increased by 28.1%. These results demonstrate the innovativeness of our new electrochemical wet-spinning process.