Modeling the effects of pH and ionic strength on swelling of anionic polyelectrolyte gels

A. D. Drozdov, J. DeClaville Christiansen

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

A constitutive model is developed for the elastic response of an anionic polyelectrolyte gel under swelling in water with an arbitrary pH and an arbitrary molar fraction of dissolved monovalent salt. A gel is treated as a three-phase medium consisting of a solid phase (polymer network), solvent (water), and solute (mobile ions). Transport of solvent and solute is thought of as their diffusion through the polymer network accelerated by an electric field formed by mobile and fixed ions and accompanied by chemical reactions (dissociation of functional groups attached to polymer chains and formation of ion pairs between bound charges and mobile counter-ions). Constitutive equations are derived by means of the free energy imbalance inequality for an arbitrary three-dimensional deformation with finite strains. These relations are applied to analyze equilibrium swelling diagrams on poly(acrylic acid) gel, poly(methacrylic acid) gel, and three composite hydrogels under water uptake in a bath (i) with a fixed molar fraction of salt and varied pH, and (ii) with a fixed pH and varied molar fraction of salt. To validate the ability of the model to predict observations quantitatively, material constants are found by matching swelling curves under one type of experimental conditions and results of simulation are compared with experimental data in the other type of tests.

Original languageEnglish
Article number055005
JournalModelling and Simulation in Materials Science and Engineering
Volume23
Issue number5
DOIs
StatePublished - 1 Jul 2015
Externally publishedYes

Keywords

  • constitutive modeling
  • finite elasticity
  • polyelectrolyte gel
  • swelling

ASJC Scopus subject areas

  • Modeling and Simulation
  • Materials Science (all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Computer Science Applications

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