WIAS Preprint No. 2562, (2018)

Surface induced phase separation of a swelling hydrogel


  • Hennessy, Matthew G.
  • Münch, Andreas
  • Wagner, Barbara
    ORCID: 0000-0001-8306-3645

2010 Mathematics Subject Classification

  • 74H10 82C26

2010 Physics and Astronomy Classification Scheme

  • 83.80.Rs, 83.10.Tv


  • Hydrogel, asymptotic analysis, nonlinear elasticity, phase transition




We present a formulation of the free boundary problem for a hydrogel that accounts for the interfacial free energy and finite strain due to the large deformation of the polymer network during solvent transport across the free boundary. For the geometry of an initially dry layer fixed at a rigid substrate, our model predicts a phase transition when a critical value of the solvent concentration has been reached near the free boundary. A one-dimensional case study shows that depending on the flux rate at the free boundary an initial saturation front is followed by spinodal decomposition of the hydrogel and the formation of an interfacial front that moves through the layer. Moreover, increasing the shear modulus of the elastic network delays or even suppresses phase separation.

Appeared in

  • Phys. Rev. E, 101 (2020), 032501, DOI 10.1103/PhysRevE.101.032501 with the new title ``Phase separation in swelling and deswelling hydrogels with a free boundary'' .

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