Modelling, in tandem with morphological, mechanical, and transport experimental evidence, can be a powerful tool to deconstruct how different stimuli can be designed to elicit a desired response from an ionomer. A large majority of relevant models have dealt with transport in and mechanics of Nafion membranes as isolated behaviors. Transport models, which are usually continuum scale, use dilute solution (Nernst–Planck) or concentrated solution (Onsager–Stefan–Maxwell) theory depending on the scale and complexity of the phenomena in focus. Mechanical models range from statistical-mechanics-led molecular scale formulations to macroscopic phenomenological approaches. Whereas the continuum models lose out on details regarding morphological changes, molecular models are simply too expensive to scale up. Mesoscale models can offer an elegant solution for this problem by incorporating phenomenon inseparable from structural details of the material while remaining computationally tenable.
In this work, the hydrophilic and hydrophobic domains in the ionomer will be modelled as two-way coupled mesoscale networks. Whereas the transport network will share characteristics with a pore-network-like configuration, the polymeric backbone will be visualized as a network of non-Hookean springs. The interspersed networks will be configured using the dual-cubic as well as the Delaunay–Voronoi conformations. The mathematical frameworks for each phase will also be modified to include mass-momentum coupling, as implemented by a few continuum models. The network nature of the topology will allow for local flux and deformation changes to organically propagate beyond the nearest neighbors, capturing the core of the ionomer’s responsiveness. Deeper insights into the stimuli-response behavior will allow for more nuanced control of operating conditions for fuel cells and electrolyzers to obtain a tailored performance from existing ionomers as well as enable development of better customized materials for the future.