Moving Ion Exchange Fronts in Polyelectrolyte Gels

Gehrke, Stevin H.; Agrawal, G. G.; Yang, Ming‐Chien

doi:10.1021/bk-1992-0480.ch013

Cited by 7 publications

(5 citation statements)

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“…Since T = 100 s, these results indicate swelling times on the order of minutes for the centimeter-scale gels. Such swelling times are also consistent with the experimental measurements of Gehrke et al (1992).…”

Section: Kineticssupporting

confidence: 91%

“…These curves were obtained using the parameter values given in Table 1 and the values of U c and U th . We note that these curves bear a strong qualitative resemblance to the experimental results of Gehrke et al (1992). Since T = 100 s, these results indicate swelling times on the order of minutes for the centimeter-scale gels.…”

Section: Kineticssupporting

confidence: 76%

“…As an approximation, the theory is specialized to the situation in which the motion of the interface is slow compared to the diffusion in the bulk phases, as is suggested by the experimental observations of Gehrke et al (1992). This results a system of governing equations where the coupling between the deformation and solute concentration is solely through the normal configurational force balance which holds across the interface.…”

Section: Summary and Concluding Remarksmentioning

confidence: 99%

“…This model was later extended to the spherically symmetric case by Tomari and Doi (1995), where the authors employed a Flory-Huggins type free-energy functional for ionic gels in a neutral solution. For pH-sensitive gels, Gehrke et al (1992) adopted a classical shrinking core model to cylindrical configurations and correlated their results to experimental measurements of the motion of the sharp ionization front. Their model did not consider large volume changes and the diffusion coefficients obtained from the correlation process were found to be significantly lower than those reported elsewhere.…”

Section: Introductionmentioning

confidence: 99%

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Chemically induced swelling of hydrogels

Dolbow

Fried

2004

Journal of the Mechanics and Physics of Solids

147

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We present a theory for the chemically-induced volume transitions of hydrogels. Consistent with experimental observations, we account for a sharp interface separating swelled and collapsed phases of the underlying polymer network. The polymer chains are treated as a solute with an associated diffusion potential and their concentration is assumed to be discontinuous across the interface. In addition to the standard bulk and interfacial equations imposing force balance and solute balance, the theory involves an ancillary interfacial equation imposing configurational force balance. Motivated by experimental observations, we specialize the theory to the situation where the time scale associated with the interface motion is slow compared to those associated with diffusion in the bulk phases. We present a hybrid eXtended-Finite-Element/Level-Set Method (XFE/LSM) for obtaining approximate solutions to the equations arising under this specialization. As an application, we consider the swelling of a spherical specimen whose boundary is traction-free and is in contact with a reservoir of uniform chemical potential. Our numerical results exhibit good qualitative comparison with experimental observations and predict characteristic swelling times that are proportional to the square of the specimen radius. Our results also suggest several possible synthetic pathways that might be pursued as a means to engineer hydrogels with optimal response times.

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Section: Kineticssupporting

confidence: 91%

Section: Kineticssupporting

confidence: 76%

Section: Summary and Concluding Remarksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Chemically induced swelling of hydrogels

Dolbow

Fried

2004

Journal of the Mechanics and Physics of Solids

147

View full text Add to dashboard Cite

show abstract

“…This relation, a direct consequence of the free-energy imbalance Figure 5: Normalized interface position with time for spherical specimens with radii of R = 1, 2, 4, and 8 cm. These plots bear a strong qualitative resemblance to the experimental results of Gehrke, Agrawal and Yang [3].…”

Section: Unified Theory Of Evolving Interfaces With Deformation and Asupporting

confidence: 74%