Transport in polymer-gel composites: response to a bulk concentration gradient
1Department of Chemical Engineering and McGill Institute for Advanced Materials, McGill University, Montreal, Quebec H3A 2B2, Canada. reghan.hill@mcgill.ca
The Journal of Chemical Physics
|January 18, 2006
Summary
Charged inclusions in polymer gels alter ion diffusion and create electric fields due to concentration gradients. This affects how electrolytes behave, potentially reversing their symmetry and driving fluid flow.
Area of Science:
- Electrokinetics
- Polymer science
- Colloid science
Background:
- Previous work established an electrokinetic model for electrolyte-saturated polymer gels.
- Homogeneous composites' response to electric fields was previously calculated.
Purpose of the Study:
- To compute the influence of charged spherical inclusions on bulk ion fluxes in polymer gels.
- To determine the electric field strength induced by electrolyte concentration gradients within these composites.
Main Methods:
- Utilizing an electrokinetic model for electrolyte-saturated polymer gels with charged inclusions.
- Calculating bulk ion fluxes and induced electric field strength.
- Quantifying flow driven by concentration-gradient-induced diffuse double layer perturbations.
Main Results:
- Inclusions significantly alter effective ion diffusion coefficients.
- Asymmetric electrolytes can exhibit symmetrical behavior and vice versa, depending on inclusion surface charge.
- The theory quantifies flow driven by concentration gradients, which can be up or down the gradient.
Conclusions:
- Charged inclusions play a critical role in the electrokinetic response of polymer gels.
- The presence of inclusions can fundamentally change the diffusive and fluid transport properties of electrolyte-filled gels.
- This study provides a theoretical framework for understanding complex transport phenomena in heterogeneous porous media.
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