Study on morphology of electrospun poly(vinyl alcohol) mats

Submicron poly(vinyl alcohol) (PVA) fiber mats were prepared by electrospinning of aqueous PVA solutions in 68% concentration. Fiber morphology was observed under a scanning electron microscope and effects of instrument parameters including electric voltage, tip-target distance, flow rate and solution parameters such as concentration on the morphology of electrospun PVA fibers were evaluated. Results showed that, when PVA with higher degree of hydrolysis (DH) of 98% was used, tip-target distance exhibited no significant effect on the fiber morphology, however the morphological structure can be slightly changed by changing the solution flow rate. At high voltages above I 10kV, electrospun PVA fibers exhibited a broad diameter distribution. With increasing solution concentration, the morphology was changed from beaded fiber to uniform fiber and the average fiber diameter could be increased from 87 +/- 14 nm to 246 +/- 50 nm. It was also found that additions of sodium chloride and ethanol had significant effects on the fiber diameter and the morphology of electrospun PVA fibers because of the different solution conductivity, surface tension and viscosity. When the DH value of PVA was increased from 80% to 99%, the morphology electrospun PVA fibers was changed from ribbon-like fibers to uniform fibers and then to beaded fibers. The addition of aspirin and bovine serum albumin also resulted in the appearance of beads. (C) 2004 Elsevier Ltd. All rights reserved.