Electrospinning of Poly(vinyl pyrrolidone): Effects of Solvents on Electrospinnability for the Fabrication of Poly(p-phenylene vinylene) and TiO2 Nanofibers

Seven different solvents (methanol, ethanol, 2-propanol, 1,2-dichloroethane, water, chloroform, and dichloromethane) were used to prepare electrospun poly (vinyl pyrrolidone) (PVP) fibers. The dielectric constant, viscosity, and surface tension of the solvents essentially affected the electrospinnability, morphological appearance, and size of the as-spun fibers. Small and uniform as-spun fibers could be fabricated from PVP solutions in solvents with a significantly high dielectric constant, low surface tension, and low viscosity. In three alcohol solutions (e.g., methanol, ethanol, and 2-propanol), the diameters of as-spun PVP fibers decreased with the dielectric constant, dipole moment, and density of the solvents increasing and with the viscosity of the solvents decreasing. Among these solvents, methanol was the best solvent, providing fibers with an optimal morphological appearance and a small fiber diameter. Mixing an unspinnable solvent with a solvent with a high dielectric constant, low surface tension, and low viscosity could increase the electrospinnability of the solution. The effects of solution properties and spinning conditions on the morphological appearance and diameter of electrospun PVP fibers were also carefully investigated. Under all investigated conditions for the electrospinning of a PVP solution in ethanol, the average diameters of the as-spun fibers ranged from 200 nm to 1.5 mu m. Well-aligned PVP fibers were also produced with a rotating-drum collector technique. Lastly, PVP was used in the fabrication of poly[2-methoxy-5-(2'-ethythexyloxy)-1,4-phenylene-vinylene] and TiO2 fibers by acting as a polymer carrier or guide. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 2777-2791, 2009