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

Poly(vinyl alcohol) (PVA) was modified with phthalic and succinic anhydride s to produce vinyl alcohol-vinyl ester copolymers that contain free carboxy lic acid or carboxylate groups. These half-esters were then crosslinked usi ng the diglycidylether of 1,4-butanediol. Low crosslinker/carboxylic acid r atios were used to obtain low degrees of crosslinking, so that the capacity to absorb water of the resulting hydrogel was high. Water absorption was d etermined gravimetrically as a function of time at room temperature. The sw elling behavior was significantly different in both ionic and nonionic poly mers. The water uptake of the former was high enough for products to be con sidered superabsorbents. (C) 2001 John Wiley & Sons, Inc.