Diffusion coefficient, porosity measurement, dynamic and equilibrium swelling studies of acrylic acid/polyvinyl alcohol

Objective of the present work was to synthesize hydrogels of acrylic acid/polyvinyl alcohol (AA/PVA) by free radical polymerization by using glutaradehyde (GA) as crosslinkers. The hydrogels were evaluated for swelling, diffusion coefficient and network parameters like the average molecular weight between crosslink's, polymer volume fraction in swollen state, number of repeating units between crosslinks and crosslinking density by using Flory-Huggins theory. It was found that the degree of swelling of AA/PVA hydrogels increases greatly within the pH range 5-7. The gel fraction and porosity increased by increasing the concentration of AA or PVA. Increase in degree of crosslinking, decreased the porosity and inverse was observed in gel fraction. Selected samples were loaded with metoprolol tartrate. Drug release was studied in USP hydrochloric acid solution of pH 1.2 and phosphate buffer solutions of pH 5.5 and 7.5. Various kinetics models like zero order, first order, Higuchi and Peppas model were used for in vitro kinetic studies. The results showed that the drug release followed concentration dependent effect (First order kinetics) with non-Fickian diffusion. FTIR and SEM used to study the structure, crystallinity, and morphology of prepared and drug loaded hydrogels respectively.