Preparation of Fully Hydrolyzed Ultra-High-Molecular-Weight Polyvinyl Alcohol Nanofibers by Viscosity Control and Improvement of Fiber Hot Water Resistance by Annealing

Fully hydrolyzed ultra-high-molecular-weight polyvinyl alcohol (PVA) electrospun fibers with uniform diameters of about 200 nm were fabricated by reducing the viscosity of PVA in aqueous solution. A novel viscosity-modifier (hydrazine monochloride, HMC) gradually reduces the viscosity of PVA aqueous solution over a period of several days. This phenomenon is counter to the usual effect of ionic salt addition. After being stored for several days, the viscosity decreased by up to 60 % compared to that of an equivalent pure PVA solution. Using HMC to control the viscosity of the PVA solution made it possible to fabricate ultrafine electrospun fibers. In addition, the hot water resistance of the fibers was obviously improved by annealing.