Transient simulation for kinetic responsive behaviors of electric-sensitive hydrogels subject to applied electric field

Abstract

In this paper, the kinetics of polymer-based electric-stimulus-responsive hydrogels is investigated numerically. The studied hydrogels are mainly composed of three phases, i.e. the interstitial water, mobile ions and a three-dimensional networked structure of hydrophilic polymer-chains crosslinked to each other. With consideration of the chemo-electro-mechanical coupling effect and the multi-phasic (water, ion and polymer-based solid phases) interactions, a newly developed mathematical model, called the multi-effect-coupling electric-stimulus (MECe) model, is briefly presented to simulate the responsive behaviors of electric-sensitive hydrogels immersed into a bath solution under an externally applied electric field. The full formulation of the MECe model is expressed by a set of nonlinear partial differential equations, consisting of the Nernst-Plank equations for the concentration distributions of diffusive ionic species, the Poisson equation for the pattern of electric potential, and the continuum mechanical equation for the mechanical deformation of hydrogels. In order to solve the complex MECe model, a novel meshless Hermite-Cloud method is used in numerical implementations. The simulations in this paper focus on the one-dimensional transient analysis for the kinetics of the hydrogels. After the validation of the developed MECe model by comparing the steady-state numerical results with the experiments, this paper presents the transient simulations for variations of the ionic concentration and average curvature of hydrogels. The simulating results of the kinetic hydrogel indicate that the electric-sensitive hydrogels respond rapidly to the external electric-stimulus before a critical time and then no significant further response occurs after the critical time. © 2005 Elsevier B.V. All rights reserved.