Structure-property relations for equilibrium swelling of cationic gels

•Governing equations are reported for equilibrium swelling of cationic gels.•The ability of the model to predict observations is confirmed by simulation.•Relations are established between material constants and composition of a gel.

Governing equations are developed for equilibrium swelling of a cationic polyelectrolyte gel in aqueous solutions with various pH and molar fractions of a monovalent salt. Material constants are determined by fitting observations on several homo- and copolymer gels in two types of tests: when swelling is conducted in water baths with varied pH and a fixed molar fraction of salt, and when experiments are performed in water baths with a fixed pH and varied concentration of salt. Phenomenological relations are suggested for the effect of total volume fraction of monomers in a pre-gel solution, molar fraction of ionic monomers, and molar fraction of cross-linker on adjustable parameters in the model.

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