Hydrogels from glycidyl derivatives of poly(vinyl alcohol)

Poly(vinyl alcohol) (PVA) was modified with phthalic anhydride to obtain half esters with carboxylic acid groups, which made the reaction with epichlorohydrin easier. The oxirane ring underwent a further crosslinking that led to crosslinked polymers with polar groups capable of interacting strongly with water and therefore with properties of hydrogels. The curing kinetics of the crosslinking were studied by differential scanning calorimetry, and the dependence of the activation energy on conversion degree was studied by isoconversional kinetic analysis. Water absorption was determined gravimetrically as a function of time at room temperature. The swelling behavior of these hydrogels was related to the degree of crosslinking. (C) 2002 Wiley Periodicals, Inc.