The transport of charge due to electric stimulus is the primary mechanism of actuation for a class of polymeric active materials known as ionomeric polymer transducers (IPTs). A two-dimensional ion hopping model has been built to describe ion transport in the IPT. In a Monte Carlo simulation, a square lattice of 50nm × 50nm is investigated containing 200 cations and 200 anions. Step voltages are applied between the electrodes of the IPT, causing the thermally-activated hopping between multiwell energy structures. The energy barrier height includes three parts: intrinsic energy, energy height due to the electric field and energy height due to ion-ion interactions. Periodic boundary conditions have been applied in the direction perpendicular to the electric field. The influence of the electrodes on both faces of IPT is formulated by the method of image charges. The charge density profile over the material has been calculated by the ion distribution in steady state. The Monte Carlo simulation is repeated multiple times to obtain an average result of the charge density. The averaged profile shows regions of cation depletion close to the anode, charge neutrality in the central part and ion accumulation close to the cathode, which qualitatively agrees with the results from conventional continuum models. To quantatively examine the Monte Carlo simulation of the ion hopping model, comparisons with a computational model of transport and electromechanical transduction are performed. This computational model is based upon a coupled chemo-electrical multi-field formulation and computes the spatio-temporal charge density profile to an applied potential at the boundaries. It can be seen that both methods, the statistical theory and the continuum theory, match quite well and are both able to represent the actual behavior inside the IPT. Moreover, experiments are performed to validate the current density calculated by the Monte Carlo simulation. The active material is Nafion 117 (Dupont) in the form of a cantilevered transducer with conductive electrodes on both surfaces and with mobile Na+ counter-ions. Voltage inputs are provided by a dSPACE DS 1102 DSP and amplified using an HP power amplifier. The current is measured by placing a small resistor in series with the sample, between the sample and ground. The voltage across the resistor is amplified and measured by dSPACE. The electrical current is calculated by dividing the voltage drop across the resistor by its resistance. Current density in both simulation results and experimental results exhibits an exponential decay over time.

1.
Salomon
R.
,
Sadeghipourt
K.
and
Neogi
S.
, “
Development of a novel electrochemically active membrane and ‘smart’ material based vibration sensor/damper
”.
Smart Materials and Structures
,
1
:
172
179
,
1992
.
2.
M. A. Buechler and D. J. Leo, “Electromechanical model of an active polymer thin circular disk”, Proceedings of ASME International Mechanical Engineering Congress and Exposition, IMECE 2004-61477, 2004.
3.
A. Etebari, B. J. Akle, K. Farinholt, M. Bennett, D. J. Leo and P. P. Vlachos, “The use of active ionic polymers in dynamic skin friction measurements”, Proceedings of ASME Heat Transfer/Fluids Engineering Conference, HT-FED2004-56837, 2004.
4.
Newbury
K. M.
and
Leo
D. J.
, “
Linear electromechanical model of ionic polymer transducers - part i: Model development
”,
Journal of intelligent material systems and structures
,
14
:
333
342
,
2003
.
5.
Piffaretti
F.
,
Gassert
R.
,
Nakao
M.
,
Nakano
M.
,
Mazzone
A.
and
Bleuler
H.
, “
Ipmc actuator array as 3-d haptic display
”,
Proceedings of SPIE
,
5759
:
331
339
,
2005
.
6.
Munn
G. E.
,
Gierke
T. D.
and
Wilson
F. C.
, “
The morphology in nafion perfluorinated membrane products, as determined by wide- and small-angle x-ray studies
”,
Journal of Polymer Science: Polymer Physics Edition
,
19
:
1687
1704
,
1981
.
7.
Barkley
J. R.
,
Hsu
W. Y.
and
Meakin
P.
, “
Ion percolation and insulator-to-conductor transition in nafion perfluorosulfonic acid membranes
”,
Macromolecules
,
13
:
198
200
,
1980
.
8.
Datye
V. K.
and
Taylor
P. L.
, “
Simple model for clustering and ionic transport in ionomer membranes
”,
Macromolecules
,
17
:
1704
1708
,
1984
.
9.
Nemat-Nasser
S.
and
Li
J. Y.
, “
Electromechanical response of ionic polymer-metal composites
”,
Journal of Applied Physics
,
87
(
7)
:
3321
3331
,
2000
.
10.
Weiland
L. M.
and
Leo
D. J.
, “
Electrostatic analysis of cluster response to electrical and mechanical loading in ionic polymers with cluster morphology
”,
Smart Materials and Structures
,
13
:
323
336
,
2004
.
11.
Weiland
L. M.
and
Leo
D. J.
, “
Computational Analysis of Ionic Polymer Cluster Energetics
”,
Journal of Applied Physics
,
97
, pp.
013541
-
1
,
2005
.
12.
Weiland
L. M.
and
Leo
D. J.
, “
Ionic Polymer Cluster Energetics: Computational Analysis of Pendant Chain Stiffness and Charge Imbalance
”, accepted to the
Journal of Applied Physics
,
97
,
123530
123530
,
2005
.
13.
Leo
D. J.
,
Wallmersperger
T.
and
Farinholt
K.
. “
Computational models of ionic transport and electromechanical transduction in ionomeric polymer transducers
”,
Proceedings of SPIE
,
5759
:
170
181
,
2005
.
14.
Wagner
A.
and
Kliem
H.
. “
Dispersive ionic space charge relaxation in solid polymer electrolytes. ii model and simulation
”,
Journal of Applied Physics
,
91
:
6638
6649
,
2002
.
15.
X. He and D. J.Leo, “Monte Carlo simulation of ion transport at the polymer-metal interface”, Proceedings of the ASME International Mechanical Engineering Congress & Exposition, paper number IMECE2005-79765, 2005
16.
X. He and D. J. Leo. “Monte carlo simulation of ion transport of high strain ionomer with cluster morphology”, Proceedings of SPIE, (Paper number: 6166-20), 2006.
17.
Elimes
A.
,
Scarle
S.
,
Sterzel
M.
and
Munn
R. W.
, “
Monte carlo simulation of Li+ motion in polyethylene based on polariztion energy calculations and informed by data compression analysis
”,
The Journal of Chemical Physics
,
123
:
154909
154909
,
2005
.
18.
K. C. David, Field and wave electromagnetics. Addison-Wesley, 1983.
19.
Wallmersperger
T.
,
Kro¨plin
B.
,
Gu¨lch
R. W.
, “
Coupled chemo-electro-mechanical formulation for ionic polymer gels–numerical and experimental investigations
”,
Mechanics of Materials
, Vol.
36
,
5–6
, pp.
411
420
, Coupled Chemo-Mechanical Phenomena,
2004
20.
T. Wallmersperger, B. Kro¨plin, R.W. Gu¨lch, “Modeling and analysis of chemistry and electromechanics”, Electroactive Polymer (EAP) Actuators as Artificial Muscles - Reality, Potential and Challenges, Second Edition, Y. Bar-Cohen (Ed.). SPIE press, 335–362, PM 136, 2004
21.
K. M. Newbury. “Modeling, characterization, and control of ionic polymer transducers”. PhD thesis, Virginia Polytechnic Institute and State University, Blacksburg, VA, 2002.
This content is only available via PDF.
You do not currently have access to this content.