Investigation of solute permeation across hydrogels composed of poly(methyl vinyl ether-co-maleic acid) and poly(ethylene glycol).

OBJECTIVES: Swelling kinetics and solute permeation (theophylline, vitamin B(12) and fluorescein sodium) of hydrogels composed of poly(methyl vinyl ether-co-maleic acid) (PMVE/MA) and poly(ethylene glycol) (PEG) are presented.
METHODS: The effects of PMVE/MA and PEG 10 000 content on swelling behaviour (percentage swelling, the type of diffusion and swelling rate constant) were investigated in 0.1 m phosphate buffer. Network parameters, such as average molecular weight between crosslinks (M(c)) and crosslink density, were evaluated. KEY
FINDINGS: The percentage swelling and M(c) of hydrogels increased with decrease in PMVE/MA content, where the water diffusion mechanism into the hydrogels was Class-II type. In contrast, increase in PMVE/MA content caused an increase in the crosslink density. Permeation of theophylline, vitamin B(12) and fluorescein sodium, with increasing hydrodynamic radii, was studied through the equilibrium swollen hydrogels composed of PMVE/MA and PEG. In general, the permeability and diffusion coefficients of all three solutes decreased with increase in the PMVE/MA content. In addition, permeability and diffusion coefficient values increased with decreases in the hydrodynamic radii of the solute molecules.
CONCLUSIONS: The hydrogels have shown a change in swelling behaviour, crosslink density, M(c) and solute permeation with change in PMVE/MA content, thus suggesting a potential application in controlled drug-delivery systems.