Modeling of ionic transport in electric-stimulus-responsive hydrogels

This paper refines a previously developed model working on pH-sensitive hydrogels for extension of the model application to electric-sensitive hydrogels, which is called the refined multi-effect-coupling electric-stimulus (rMECe) model. The main contributions of the rMECe model comprise the reformulation of the fixed charge density and the consideration of finite deformation. The model is able to predict the ionic transport within the electric-sensitive hydrogels and the responsive behaviors of the hydrogels when immersed in a bath solution subject to externally applied electric field. The rMECe model consists of nonlinear partial differential governing equations with coupling chemo-electro-mechanical multi-energy domains, in which the fixed charge density takes account of the effect of applied electric field. For examination of the model, a numerical comparison is made between simulated results and experimental data extracted from literature and then a very good agreement is achieved. The rMECe model is employed for simulations of the electric-sensitive hydrogels. The influences of several physical parameters are discussed in detail on the distributions of diffusive ionic concentrations, including the externally applied electric voltage, the initially fixed charge density, the ionic strength and valence of bathing solution.