Ionomeric Polymer-Metal Composites

Nemat‐Nasser, Sia; Thomas, Chris W.

doi:10.1117/3.547465.ch6

Cited by 55 publications

(56 citation statements)

References 80 publications

(101 reference statements)

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“…For Nafion-based IPMCs that are neutralized with alkali metal cations and solvated by water, ethylene glycol, or glycerol, the strip then slowly relaxes back towards the cathode, while still under electric potential. 2,[4][5][6] The sample eventually reaches an equilibrium state ͑while the electric potential is still on͒, which is generally far from its initial equilibrium position. If the electric potential is removed as the two electrodes are shorted, the Nafion-based IPMC sample ͑under the above-mentioned conditions͒ displays a relatively fast bending deformation towards the cathode and then slowly relaxes back towards the anode, seldom attaining its initial state.…”

Section: B Actuation Of Ipmcsmentioning

confidence: 99%

“…1 An IPMC consists of a perfluorinated backbone ionomer ͓usually Nafion ® or Flemion ® ; ͑CF 2 CF͒ m ͑CF 2 CF 2 ͒ n ; see Fig. 1͔ plated on both faces with noble metals such as platinum, platinum and gold, or gold, and neutralized with the necessary amount of counterions that balance the electric charge of the anions covalently bonded to the ionomer. 4 The electrical-chemical-mechanical response of the IPMCs depends on the neutralizing cation, the nature of the solvent and its degree of saturation, the electrode morphology, and the chemical structure and characteristics of the backbone ionomer.…”

Section: A Composition and Propertiesmentioning

confidence: 99%

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Modeling of electrochemomechanical response of ionic polymer-metal composites with various solvents

Nemat‐Nasser¹,

Zamani²

2006

Journal of Applied Physics

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Ionic polymer-metal composites (IPMCs) consist of a perfluorinated ionomer membrane (usually Nafion® or Flemion®) plated on both faces with a noble metal such as gold or platinum and neutralized with the necessary amount of counterions that balance the electrical charge of anions that are covalently fixed to the backbone ionomer. IPMCs are electroactive materials with potential applications as soft actuators and sensors. Their electrical-chemical-mechanical response is dependent on the cations used, the nature and the amount of solvent uptake, the morphology of the electrodes, the composition of the backbone ionomer, the geometry and boundary conditions of the composite element, and the magnitude and spatial and temporal variations of the applied potential. Our most recent experimental results show that solvents can have profound effects on the nature of the IPMCs’ actuation. For example, we have discovered experimentally that Nafion-based IPMCs in Li+-form show very small back relaxation when hydrated, but extensive back relaxation with all other solvents that we have considered. On the other hand, the same membrane in the K+-form has extensive back relaxation when solvated with water, ethylene glycol, or glycerol, but none with 18-Crown-6. In the present paper, we seek to model the IPMCs’ actuation and compare results with the experimental data. The modeling rests on the observation that a sudden application of a step potential (dc) of several volts (1–3V) alters the distribution of cations within the ionomer, forcing cations out of the clusters near the anode and additional cations into the clusters near the cathode. The clusters within a thin boundary layer near the anode are thus depleted of their cations, while cations accumulate in the clusters near the cathode boundary layer. We first seek to determine the spatial and temporal variations of the cation distribution across the thickness of the IPMC for various cations and solvents, using an implicit finite difference numerical solution of the basic field equations, and compare the results with those of approximate analytical estimates. Based on this information, we then calculate the changes in the osmotic, electrostatic, and elastic forces that tend to expand or contract the clusters in the anode and cathode boundary layers. Finally, we calculate the amount of solvent out of or into the clusters that produces the bending motion of the cantilever. Comparing the model results with those of experimental measurement, we have arrived at remarkably good agreements. Indeed, our nanoscale-based model correctly predicts the unexpected influence of solvents on the actuation of IPMCs.

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Section: B Actuation Of Ipmcsmentioning

confidence: 99%

Section: A Composition and Propertiesmentioning

confidence: 99%

Modeling of electrochemomechanical response of ionic polymer-metal composites with various solvents

Nemat‐Nasser¹,

Zamani²

2006

Journal of Applied Physics

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“…1͔ plated on both faces with noble metals such as platinum or platinum and gold, or gold, and neutralized with a certain amount of counterions that balance the electric charge of the anions covalently bonded to the ionomer. 2 When a thin strip of an IPMC membrane in the solvated state is subjected to a suddenly imposed and sustained constant electric potential ͑dc͒ of several volts ͑1-3 V͒, it bends towards the anode. For Nafionbased IPMCs that are neutralized with alkali metal ions, the strip then slowly relaxes back towards the cathode, while still under electric potential.…”

Section: Introductionmentioning

confidence: 99%

Effect of solvents on the chemical and physical properties of ionic polymer-metal composites

Nemat‐Nasser¹,

Zamani²,

Tor³

2006

Journal of Applied Physics

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Ionic polymer-metal composites ͑IPMCs͒ consist of a perfluorinated ionomer membrane ͑usually Nafion® or Flemion®͒ plated on both faces with a noble metal such as gold or platinum and neutralized with a certain amount of counterions that balance the electrical charge of anions covalently fixed to the backbone ionomer. IPMCs are electroactive materials with potential applications as actuators and sensors. Their electrical-chemical-mechanical response is dependent on the cations used, the nature and the amount of solvent uptake, the morphology of the electrodes, the composition of the backbone ionomer, the geometry and boundary conditions of the composite element, and the magnitude and spatial and time variation of the applied potential. With water as the solvent, the applied electric potential must be limited to less than 1.3 V at room temperature, to avoid electrolysis. Moreover, water evaporation in open air presents additional problems. These and related factors limit the application of IPMCs with water as the solvent. We present the results of a series of tests on both Nafion-and Flemion-based IPMCs with ethylene glycol, glycerol, and crown ethers as solvents. IPMCs with these solvents have greater solvent uptake and can be subjected to relatively high voltages without electrolysis. They can be actuated in open air for rather long time periods, and at low temperatures. They may be good actuators when high-speed actuation is not necessary. In addition, their slow response in open air allows direct observation of the physical characteristics of the cathode and anode surfaces of a cantilever during actuations. This can provide additional clues for unraveling the underpinning micromechanisms of their actuation. Remarkably, solvents are found to have profound effects on the nature of the IPMCs' actuation. For example, Nafion-based IPMCs in Li + form show very small back relaxation when hydrated, but extensive back relaxation with all other solvents that we have considered. On the other hand, the same membrane in the K + form has extensive back relaxations when solvated with water, or ethylene glycol, or glycerol, but none with 18-Crown-6.

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“…For Nafion-based IPMCs that are neutralized with alkali metals, the strip then slowly relaxes back towards the cathode. This occurs while the sample is still under electric potential [Nemat-Nasser and Thomas, 2001 and Nemat-Nasser, 2002]. Experimental observations for Flemion-based IPMCs [Nemat-Nasser and Wu, 2003] show that the initial actuation towards the anode is followed by slower relaxation in the same (i.e., towards the anode) direction.…”

Section: Introductionmentioning

confidence: 99%

Controlled actuation of Nafion-based ionic polymer-metal composites (IPMCs)with ethylene glycol as solvent

Zamani

Nemat‐Nasser

2004

SPIE Proceedings

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Ionic polymer-metal composites (IPMCs) consist of a perfluorinated ionomer membrane (usually Nafion ® or Flemion ® ). The ionomer is plated on both faces with a noble metal such as gold or platinum. It is neutralized with a certain amount of counterions that balance the electrical charge of anions covalently fixed to the backbone membrane. IPMCs are electroactive materials that can be used as actuators and sensors. Their electrical-chemical-mechanical response is highly dependent on the cations used, the nature and the amount of solvent uptake, the morphology of the electrodes, and other factors. When a cantilever strip of solvated Nafion-based IPMC sample is subjected to a suddenly applied and sustained (DC) electric potential of several volts (1-3 V) across its faces, it bends towards the anode. For Nafion-based IPMCs with alkali metals, actuation towards the anode is followed by a slow back relaxation towards the cathode. If the electric potential is removed and the two electrodes are shorted during this back relaxation, the sample displays a fast bending deformation towards the cathode and then slowly relaxes back towards the anode, attaining a new equilibrium position generally distinct from its initial state. One way to change various phases of IPMC actuation is achieved by changing input potential. The electric potential inputs may be used to control the actuation of IPMCs. We present the results of a series of tests on Nafion-based IPMCs with ethylene glycol as solvent, actuated under electric potential inputs other than DC electric potential. We present experimental results for increasing ramp and sinusoidal electric potential waveforms.

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Ionomeric Polymer-Metal Composites

Cited by 55 publications

References 80 publications

Modeling of electrochemomechanical response of ionic polymer-metal composites with various solvents

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

Controlled actuation of Nafion-based ionic polymer-metal composites (IPMCs)with ethylene glycol as solvent

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