Ionic polymer gels

Non-ionic polymer gel, swollen with dielectric solvent, can be extremely deformed as is the case for non-ionic polymer plasticised with non-ionic plasticiser. Instead of the charge-injected solvent drag as a mechanism of the gel actuation, the principle is based on local asymmetrical charge distribution at the surface of the gel18. The mechanism can also be applied to non-ionic elastomers in which the motion of the polymer chain is relatively free. In spite of their many difficulties for practical actuators, polyelectrolyte gels and related materials are the most interesting electroactive polymer materials. 

Hirai T., Zheng J., Watanabe M., Electrically active polymer materials - application of non-ionic polymer gel and elastomers for artificial muscles in Tao X. (ed.) Smart Fibres, Fabrics and Clothing, Woodhead Publishing, Cambridge. 2001. 

Keywords Ionic polymer gels Modelling Numerical simulation Chemical stimulation Electrical stimulation Multi-field formulation Finite elements Discrete elements... 

WaUmersperger, T., KropUn, B. Gulch, R.W. 2004, Coupled chemo-electro-mechanical formulation for ionic polymer gels - numerical and experimental investigations . Mechanics of Materials, vol. 36, no. 5-6, pp. 411-420. 

For dense polymeric materials, a major setback in materials development is that highly selective materials are usually neither robnst nor flexible. For example, ionic polymer gels or polyelectrolytes have high water permeabiUties,... 

Kitahara proposed such a mathematical model for the third step[174], that plate deformation is caused by the surface stress due to the adsorption of atoms on the surface. Although Doi et al. theoretically demonstrated the physics of ionic polymer gels in an electric field, their study did not assume the surfactant solution[127j. 

Fig. 2.2. Deformation process of a surfactant driven ionic polymer gel illustrated with...

In this section, we report and discuss wave-shape pattern formation of surfactant-driven ionic polymer gel in constant electric fields. 

Shiga, T., Hirose, Y., Okada, A., Kurauchi, T. Bending of ionic polymer gel caused by swelling under sinusoidally varying electric fields. Journal of Applied Polymer Science 47, 113-119 (1993)... 

Doi, M., Matsumoto, M., Hirose, Y. Deformation of ionic polymer gels by electric fields. Macromolecules 25, 5504-5511 (1992)... 

Electrically active polymer materials -application of non-ionic polymer gel and elastomers for artificial muscles... 

Conventional electrically induced actuation has been carried out mostly on ionic polymer gels. The reason is simply because ionic species are highly... 

To overcome difficulties in polyelectrolytes, such as electrochemical consumption on the electrodes, we investigated the electroactive properties of the non-ionic polymer gel. 

Therefore, the authors tried to utilize non-ionic polymer gels as actuating materials with large deformation. The results show that the idea works in a far... 

Such a remarkable swift bending or crawling of a non-ionic polymer gel cannot be explained by osmotic pressure gradient, which is usually considered to be the reason for electrically induced bending in polyelectrolyte gel. As pointed out in the previous section, the solvent flow was suggested in the gel. We investigated the effect of an electric field on its flowing property. ... 

Non-ionic polymer gel swollen with dielectric solvent is shown to be extremely deformed, as is the non-ionic polymer plasticized with non-ionic plasticizer. 

Polyelectrolyte gels, often referred as ionic polymer gels are quite attractive intelligent materials. They consist of a solid phase, i.e., a polymer network with fixed charges, and a liquid phase with mobile ions. Typically these gels are immersed in a solution bath. An application of different kinds of stimuli - e.g., chemical (change of salt concentration or pH), thermal, magnetical, or electrical -leads to a new equilibrium between the different forces, such as osmotic pressure... 

Ionic polymer gels Polyelectrolyte gels Modeling Numerical simulation Statistical theory Transport model Continuum model Coupled multi-field formulation... 

Gennes P-J (eds) Physical properties of polymeric gels. Wiley, Chichester, pp 19-38 Shahinpoor M (1994) Continuum electromechanics of ionic polymer gels as artificial muscles for robotic applications. Smart Mater Struct 3 367-372 Shiga T, Kurauchi T (1990) Deformation of polyelectrolyte gels under the influence of electric field. J Appl Polym Sci 39 2305-2320... 

Figure 4 shows the temperature dependence of the molar conductivity of AMPS, PAMPS, and a PAMPS gel. In general, unlike electron conductance of metals, carriers of ionic polymer gels are ions. Hence, electrical resistance decreases as temperature increases. This trend shows an Arrhenius-type temperature dependence as seen in semiconductors. 

There is a report on the colombic force field of a polyelectrolyte gel based on the analysis of dielectric relaxation spectra. High electron density of a polymer ion forms an extremely strong coulombic field in its vicinity (see Fig. 5) [11]. This distribution diagram is obtained by the numerical calculation based on the Poisson-Boltzmann equation. An ionic polymer gel possesses a static potential well. The coimter ions that dissociated firom the polymer ions then gather arormd them and form a restricted phase. Unlike free ions, these restricted cormter ions show dielectricity. From dielectric relaxation spectra, the insight on the coulombic force field around the polymer ions and microscopic morphology of the gel can be obtained [12-15]. 

If an electrode contacts a polyelectrolyte gel that contains water and a direct current of s 10V is applied, the gel spews out water and shrinks. Such shrinkage of gels by electric stimulation is generally seen for all natural and synthetic polymers as long as they are ionic polymer gels. 

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