Multiphysics of ionic polymer–metal composite actuator

Abstract

Articles you may be interested inPhysical interpretation of deformation evolvement with water content of ionic polymer-metal composite actuator Dynamic model of ion and water transport in ionic polymer-metal composites AIP Advances 1, 040702 (2011); 10.1063/1.3668286 An explicit physics-based model of ionic polymer-metal composite actuatorsWater-based ionic polymer-metal composites (IPMCs) exhibit complex deformation properties, especially with decreasing water content. Based on our experimental understanding, we developed a systemic actuation mechanism for IPMCs in which the water swelling was taken as the basic cause of deformation. We focused on Nafion-IPMC, and formulated a multiphysical model to describe the complicated deformation properties. The model emphasizes pressure-induced convection fluxes and the significance of the water distribution on deformation. It shows that there are three eigen stresses activated by the migration of ions and water, namely, osmotic pressure, electrostatic stress, and capillary pressure. The model also provides a convenient way of simultaneously handling the internal eigen stresses and the external mechanical load. In this paper, we used a fundamental model, which only considered the hydrostatic pressure in the multiphysical model, to analyze the general transport properties of cations and water by numerical methods. Three effects were investigated: (1) the inter-coupling effects between cations and water, which slow down cation migration and attenuate the back-diffusion of water; (2) the pressure effect, which rarely influences the electric field and the cation distribution, but greatly changes the profile of the water concentration and then the deformation behavior; and (3) the hydration effect, which has a significant impact on the distribution profiles of the cations and the electrical potential. In contrast to the findings of traditional studies, the water concentration displays an almost uniform gradient across the thickness in the bulk, and the cation concentration at the cathode is greatly reduced by the volume effect of the hydrated cations. V C 2013 AIP Publishing LLC.

Modeling the response of polymer–ionic liquid electromechanical actuators

“…Most of these studies focus on the time-dependent response at the initial interval of deformation (immediately after application of voltage), presume diffusivity of positive ions to exceed strongly that of negative ions, and explain bending of a membrane by the action of ionic pressure developed in a domain rich in positive ions near the negative electrode. Although observations confirm that diffusivity of cations in a nanoporous medium is substantially higher than diffusivity of anions [51], their ratio depends strongly on concentration of ions, structure of nanochannels between pores, and distribution of bound charges at the surfaces of pores, which requires evolution of a network of nanochannels to be accounted explicitly [17,52,53].…”

Electromechanical performance of ionic polymer-metal composite under electrode constraint

“…The simulation constants are exactly the same as Table I in Zhu et al, 21 and the geometry of the sample was depicted in Figure 4(a). The governing equations of the electro-chemical field were implemented with PDE modules, while the mechanical field was with the ''plane strain'' module.…”

Effects of surface roughening on the mass transport and mechanical properties of ionic polymer-metal composite

“…One is that P is the hydrostatic pressure from the elastic stress and can be determined based on its equilibrium with the internal elastic stresses of the polymer cluster 14 as Eq. (4).…”

“…In addition, to ensure convergence, dynamic drag coefficients defined according to the Onsager reciprocal relations 14 were presented as follows:…”

“…In our previous papers, these models were critically reviewed and compared, 12 and on this basis a more comprehensive multi-physical model was formulated, which is capable of describing the complicated deformation properties of IPMC. 13,14 However, in most of the theoretical models, IPMC has been widely pictured as a polyelectrolyte membrane sandwiched between two flat electrodes, where the electrodes are regarded only as conductors to provide the electric field. As pointed by Wang,15 this structural idealization (ignorance of the interface) may lead to problematic predictions.…”