Model development of ionic-strength-sensitive hydrogel and finite element analysis of gel and dielectrics

Abstract

V quantitatively. Further, the steady-state MECis model is also compared with the modified Flory-Rehner theory-I and-II, as well as the gel-swelling model. It is demonstrated that the present MECis model can work more accurately by considering more physical and chemical environmental conditions. In addition, the four parameter studies are carried out, in order to understand how the physical and chemical parameters affect the equilibrium characteristics of the ionic-strength-sensitive hydrogel, including the influences of the initial fixed charge density, the equilibrium constant, the Young's modulus, and the initial fixed charge distance on the equilibrium characteristics. The influence of these parameters is presented in terms of the swelling ratio, the chemical, electric and mechanical fields, where the distributions of several important field variables are analyzed in details, such as the fixed charge density, the ionic concentration, the electric potential, and the displacement. Apart from that, the kinetics of the ionic-strength-sensitive hydrogel is also analyzed by the transient MECis simulation, where the present model is employed first to investigate the kinetics of the swelling/shrinking and/or reversible properties of various ionic-strength-sensitive hydrogels, and then compared with the corresponding experiments. The comparisons show that the MECis model is capable of modeling and simulating of the kinetic characteristics of the ionic-strength-sensitive hydrogels accurately. The influence of the chemical and physical parameters is then studied systematically on the kinetic swelling/shrinking of the ionic-strength-sensitive hydrogel, where the reversible kinetics and the influences of the initial fixed charge density and Young's modulus on the kinetics of the hydrogel are discussed in details. The kinetics of the swelling ratio with different parameters, and the kinetic distributions of the significant field variables are analyzed as well, including the fixed charge density, the ionic concentration, the electric potential, and the displacement. Finally, the finite element methods are implemented for the investigation of the kinetic deformation of the gels in water and the equilibrium of dielectrics, respectively. Firstly, the kinetic deformation patterns of the gels with various shapes and constraints in water are analyzed by the finite element model, including the constrained, the block, the thin film, and the bonded gels, where different deformation patterns are achieved, such as the buckling, twisting, wrinkling, folding, and waving. The experiments are also carried out to observe the swelling and wrinkling of the cubic and thin film gels. The simulation is compared with the experiments and a good agreement is observed.