Improvement of the water resistance of atactic poly(vinyl alcohol) nanowebs by a heat treatment

Nanoscale materials can be rationally designed to exhibit significantly changed physical, chemical, and biological properties because of the extremely small dimensions. Therefore, atactic poly(vinyl alcohol) (a-PVA) nanowebs by an electrospinning technique have very high water solubility because of their nanoscale in comparison with microscale materials such as fibers and films. In this study, a-PVA nanowebs were prepared via electrospinning under suitable conditions to form PVA webs with uniform nanofibers (fiber average diameter = 200 +/- 50 nm), not a bead or bead-and-string morphology. Furthermore, to improve the water resistance of the water-soluble a-PVA nanowebs, the PVA nanotures. The melting temperature of the heat-treated PVA nanowebs shifted toward a lower temperature with an increase in the heat-treatment temperature, and this indicated that micronetwork domains formed. Moreover, with the exception of a PVA nanoweb treated at an excessive heat-treatment temperature, the heat-treated PVA nanowebs showed higher crystalline and mechanical properties than a pure PVA nanoweb. (c) 2007 Wiley Periodicals, Inc.