Synthesis and characterization of noncrosslinked and crosslinked poly [vinyl alcohol-co-crotonc acid] hydrogels

ABSTRACT

The aim of this work was to investigate the possibility of combining hydrophilic [VAL] monomer with crotonic acid [CA] monomer and to explore their potential for drug delivery. Six noncrosslinked poly[vinyl acetate-co-crotonic acid] [VAC/CA] samples 5050 to 9505 mole% were prepared. The monomer feed ratio affects the molecular weight and the polymerization hindered by increasing the CA traction in the monomer mixture. This is most probably due to differences in reactivity ratios. All the samples were hydrolysed in methanolic KOH solution. Salt form was converted into acid form by adding acetic acid. In poly[vinyl alcohol-co-crotonic acid] [VAL/CA] polymers, the OH and the COOH groups seem to be partially involved in a lactonized form. By increasing the COOH groups, the amount of OH groups reduced through lactone ring formation. The COOH groups are few in numbers and might be at scattered positions in the chain, making the gels unable to show pH-sensitivity. One sample of VAL/CA containing monomeric composition [VAC/CA 90 10] was crosslinked with glutaraldehyde, with various crosslinking ratios. A remarkable effect of crosslinking ratio was observed on swelling and phenazone release