Preparation and properties of glutaraldehyde crosslinked poly(vinyl alcohol) membrane with gradient structure

Abstract

Poly(vinyl alcohol) (PVA) is an attractive polymer for various applications based on membranes. To increase water resistance, PVA material has to be adequately crosslinked. However, crosslinking behavior on the whole PVA membrane generally leads to obviously increased brittleness and deteriorated transparency. In the present research, a kind of glutaraldehyde crosslinked PVA membrane with gradient structure has been successfully designed and prepared by the casting membrane of pure PVA aqueous solution and the following surface post-crosslinking processes. The method can endow the PVA membrane with the gradiently decreased crosslinking degree from the surface to inside. Such gradient cross-linked PVA membrane not only keeps good flexibility and transparency, but also possesses satisfactory water-proof property. The structure and properties of the prepared the gradient acetalized PVA (GAPVA) membranes were analyzed and characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscope (SEM), tensile measurement, water resistance test and transparency observation, etc. Compared with pure PVA membrane and uniform acetalized PVA (UAPVA) one, such GAPVA membrane displays excellent performance including good water resistance, transparency and mechanical properties, much higher than those of UAPVA membrane.