Multiple Phases in Ionic Copolymer Gels

This study presents a theoretical description of multiple phases in ionic copolymer gels. The equations for the dissociation equilibrium of the fixed charges in the gel are solved together with a Flory-type swelling model which incorporates both polyelectrolyte and polyampholyte effects. This model correctly predicts the qualitative shape of the gel swelling vs $p\mathrm{H}$ curve. Although several phases could appear when hydrogen bonding effects are significant, the possibility of having very long relaxation times due to the slow ion exchange kinetics in the gel should be carefully examined.