Synthesis and swelling characteristics of acid-containing poly(vinyl alcohol) hydrogels

Poly(vinyl alcohol) (PVA) was modified with phthalic and succinic anhydrides to produce vinyl alcohol-vinyl ester copolymers that contain free carboxylic acid or carboxylate groups. These half-esters were then crosslinked using the diglycidylether of 1,4-butanediol. Low crosslinker/carboxylic acid ratios were used to obtain low degrees of crosslinking, so that the capacity to absorb water of the resulting hydrogel was high. Water absorption was determined gravimetrically as a function of time at room temperature. The swelling behavior was significantly different in both ionic and nonionic polymers. The water uptake of the former was high enough for products to be considered superabsorbents. (C) 2001 John Wiley & Sons, Inc.