Electrical conductivity of pH-responsive hydrogels

J Biomater Sci Polym Ed. 1997;8(5):349-62. doi: 10.1163/156856297x00146.

Abstract

The electrical conductivity of pH-responsive hydrogels based on cross-linked poly(2-hydroxyethyl methacrylate-co-dimethylaminoethyl methacrylate) copolymers has been studied as a function of pH over the range 5-10, for copolymers containing up to 20 mol% of the amine-containing comonomer. The conductivities of membranes equilibrated in buffered potassium chloride solutions were determined by measuring the electrical resistance of a membrane mounted between the chambers of a modified side-by-side diffusion cell. The conductivity, expressed as a fraction of the conductivity of the buffer in which the gels were equilibrated, ranged from 1% for the gels in the collapsed state to 70% for the most highly swollen gels. The observed results are qualitatively consistent with a proposed model in which the ion concentrations in the fluid phase of the gel are described by Donnan partitioning, and the ion mobilities by the free-volume theory of Yasuda. The results suggest that conductivity measurements may provide an alternative to diffusive transport studies for characterizing moderately swollen hydrogel membranes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cross-Linking Reagents / chemistry
  • Diffusion
  • Electric Conductivity
  • Gels
  • Hydrogen-Ion Concentration
  • Indicators and Reagents / chemistry
  • Mathematics
  • Membranes, Artificial
  • Methacrylates / chemistry*
  • Polymers
  • Potassium Chloride / chemistry

Substances

  • Cross-Linking Reagents
  • Gels
  • Indicators and Reagents
  • Membranes, Artificial
  • Methacrylates
  • Polymers
  • Potassium Chloride
  • hydroxyethyl methacrylate
  • 2-(dimethylamino)ethyl methacrylate