Physical characteristics of poly (vinyl alcohol) solutions in relation to electrospun nanofiber formation

Nanofibers prepared from poly (vinyl alcohol) (PVA) using the electrospinning process have received a great deal of attention over the past decade due to their outstanding characteristics and their applicability in the field of biomedicine, coupled with their innovative preparation. However, the success of the electrospinning process depends strongly on the parameters of the source polymer solution. Of these parameters the majority of published papers routinely examine the viscosity, conductivity and surface tension, while other, indeed crucial, physical characteristics are only rarely investigated. In the present work, the emphasis was also on a comprehensive investigation of the bulk and interfacial rheology as well as on the small-angle X-ray scattering (SAXS) of PVA solutions. A detailed analysis revealed rearrangements of the molecules in the solutions depending on the polymer concentration proved by measured surface tension, determined apparent specific volume and radius of gyration. Further, we found out that smooth nanofibers are formed only from those PVA solutions, where properly firm internal polymer structures that can be oriented in the direction of an applied electric field, enable complete polymer elongation during the electrospinning. It is important to note that this is the first time that such an extensive study has been made and, our findings provide a better insight into the physical properties of the solutions for electrospinning as well as their decisive influence on the formation of the nanofibers.