Micromechanics of actuation of ionic polymer-metal composites

Abstract

Articles you may be interested inA self-oscillating ionic polymer-metal composite bending actuator J. Appl. Phys. 103, 084908 (2008); 10.1063/1.2903478 Modeling of electrochemomechanical response of ionic polymer-metal composites with various solvents Effect of solvents on the chemical and physical properties of ionic polymer-metal composites Comparative experimental study of ionic polymer-metal composites with different backbone ionomers and in various cation forms J. Appl. Phys. 93, 5255 (2003); 10.1063/1.1563300Electromechanical response of ionic polymer-metal composites Ionic polymer-metal composites ͑IPMCs͒ consist of a polyelectrolyte membrane ͑usually, Nafion or Flemion͒ plated on both faces by a noble metal, and is neutralized with certain counter ions that balance the electrical charge of the anions covalently fixed to the backbone membrane. In the hydrated state ͑or in the presence of other suitable solvents͒, the composite is a soft actuator and sensor. Its coupled electrical-chemical-mechanical response depends on: ͑1͒ the chemical composition and structure of the backbone ionic polymer; ͑2͒ the morphology of the metal electrodes; ͑3͒ the nature of the cations; and ͑4͒ the level of hydration ͑solvent saturation͒. A systematic experimental evaluation of the mechanical response of both metal-plated and bare Nafion and Flemion in various cation forms and various water saturation levels has been performed in the author's laboratories at the University of California, San Diego. By examining the measured stiffness of the Nafion-based composites and the corresponding bare Nafion, under a variety of conditions, I have sought to develop relations between internal forces and the resulting stiffness and deformation of this class of IPMCs. Based on these and through a comparative study of the effects of various cations on the material's stiffness and response, I have attempted to identify potential micromechanisms responsible for the observed electromechanical behavior of these materials, model them, and compare the model results with experimental data. A summary of these developments is given in the present work. First, a micromechanical model for the calculation of the Young modulus of the bare Nafion or Flemion in various ion forms and water saturation levels is given. Second, the bare-polymer model is modified to include the effect of the metal plating, and the results are applied to calculate the stiffness of the corresponding IPMCs, as a function of the solvent uptake. Finally, guided by the stiffness modeling and data, the actuation of the Nafion-based IPMCs is micromechanically modeled. Examples of the model results are presented and compared with the measured data.

Dynamic model of ion and water transport in ionic polymer-metal composites

“…(15) has been extended to the sum of electrostatic stress, osmosis pressure and elastic stress. 22 It is similar with Tadokoro model, which firstly calculates the distribution of the ion and then …”

“…For that the convection velocity is zero at the steady state, equation (17) is only suitable to calculate the steady distribution of ion. 10,22 Additionally, most of the above-mentioned NP models pay little attention to the water transport. Enikov derived a complete transport model for both ion and water molecule as the form of NP equation 35 based on the thermodynamics second law.…”

“…Equation (22) contains all the possible transport mechanisms in IPMC on the isothermal condition. Prior to numerical analysis, it is needed to make sure the physical meanings of the parameters.…”

“…It was firstly borrowed by Nemat-Nasser to set a physical model describing the ion flux of IPMCs in 2000, 10 which was improved further in 2002. 22 The equation is:…”

Artificial Muscle Technology: Physical Principles and Naval Prospects

“…Both sides of the polymer membrane are loaded with metal nanoparticles and then metal plated [75][76][77][78][79][80]. The nanoparticles balance the charging that occurs in the clusters in the boimdaiy layers of the polymer, while the metal plating increases surface conductivity.…”