WIAS Preprint No. 2731, (2020)

Spinodal decomposition and collapse of a polyelectrolyte gel


  • Celora, Giulia L.
  • Hennessy, Matthew G.
  • Münch, Andreas
  • Waters, Sarah L.
  • Wagner, Barbara

2010 Mathematics Subject Classification

  • 74A30 80A22 34B15

2008 Physics and Astronomy Classification Scheme

  • 83.80.Rs 83.10.Tv.


  • Polyelectrolyte gel, phase separation, collapse




The collapse of a polyelectrolyte gel in a (monovalent) salt solution is analysed using a new model that includes interfacial gradient energy to account for phase separation in the gel, finite elasticity and multicomponent transport. We carry out a linear stability analysis to determine the stable and unstable spatially homogeneous equilibrium states and how they phase separate into localized regions that eventually coarsen to a new stable state. We then investigate the problem of a collapsing gel as a response to increasing the salt concentration in the bath. A phase space analysis reveals that the collapse is obtained by a front moving through the gel that eventually ends in a new stable equilibrium. For some parameter ranges, these two routes to gel shrinking occur together.

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