3-Mercaptopropionic Acid-Ce(IV) Redox Couple for Preparing Cross-Linked Gels with Moderate Swelling Ratios

Abstract

3-Mercaptopropionic acidCe(IV) redox couple has been demonstrated to be useful for cross-linking polymerization of acrylamide (AAm) with N,N-methylene bis(acrylamide) (MBAA). Effects of the cross-linker ratio, acid concentration, and Ce(IV) molar ratios on swelling behavior of the resulting hydrogels have been studied. These experiments show that increasing cross-linker content has greatly reduced the equilibrium swelling ratios as expected. Interestingly, the increase in the Ce(IV) concentration (nCe(IV)=nMPA) has resulted in a decrease in the swelling ratio. Because the thiol group in 3-mercaptosuccinic acid acts as a cross-linking agent, more cross-linking occurs with an increase in the Ce(IV) concentration and Ce(III) forming in the cross-linking polymerization reaction of AAm with MBAA may provide the formation of intermolecular complexes between amide groups in polymer chains; the swelling equilibrium ratio and swelling rate decrease with an increase in their concentrations in the cross-linking polymerization reaction of AAm with MBAA. Kinetics and equilibrium swelling values have been discussed in terms of reaction parameters. (c) 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E241E248, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21270