The influence of acetic acid and ethanol on the fabrication and properties of poly(vinyl alcohol) nanofibers produced by electrospinning

In this paper, the method for the fabrication of nanofibers based on poly(vinyl alcohol) (PVA) with controlled characteristics and surface morphology from binary solvent systems has been developed. Based on the Hildebrand-Scatchard theory of solubility, the calculated Teas diagrams, which take into account intermolecular interactions, made it possible to predict the formation of low-defect nanofibers based on PVA in systems of binary solvents with a higher proportion of hydrogen bonds. As a result of the findings, ethanol was determined to be a "inappropriate" solvent for the electrospinning PVA solution, whereas water and acetic acid displayed the properties of a "appropriate" solvent. The decrease in the volume of the unit cell with a slight decrease in the overall degree of crystallinity of the substance demonstrated the dependence of the change in the crystallization mechanism during the formation of PVA nanofibers on the transition from an individual aqueous polymer solution to the water/acetic acid binary solvent system. Compared with the results obtained during the PVA nanofibers fabrication from aqueous solution, the addition of 35% by weight of acetic acid to the aqueous solution of 8 wt% PVA allowed to lower the voltage from 30 to 26 kV and to increase the fiber fabrication yield by the increase in the flow rate from 0.2 to 0.3 mL/h. We confirmed that acetic acid has no effect on the chemical properties of PVA nanofibers however did change their lattice structure and reduce crystallinity of nanofibers. Such safe systems with controlled properties are suitable ones for biological active compounds encapsulation for drug delivery.