Effect of synthesis parameters on polymethacrylic acid xerogel structures and equilibrium swelling

Hydrogels based on crosslinked polymethacrylic acid were synthesized via free-radical polymerization in aqueous solution, using N,N′-methylene bisacrylamide as a crosslinking agent and 2,2′-azobis-2-(2-imidazolin-2-yl)propane] dihydrochloride as an initiator. The influence of the reaction parameters (the neutralization degree of methacrylic acid and the initial monomer concentration) on the equilibrium swelling degree, the swelling kinetic parameters and the basic structural properties of xerogels was investigated. The change of synthesis parameters leads to the change of the basic structural parameters of xerogel, as well as the equilibrium swelling degree and the initial swelling rate of the hydrogels. It is found that there are power form relationships between the equilibrium swelling degree, the initial swelling rate and the structural xerogel’s properties and the change of the neutralization degree of monomer, i.e. the monomer concentration. The examined correlations proved that the crosslinking density is the crucial parameter which determines all the other investigated structural and swelling parameters. The article is published in the original.