Ionic Polymer Metal Composites (IPMCs) are soft electroactive polymer materials that bend in response to the voltage
stimulus (1 - 4 V). They can be used as actuators or sensors. In this paper, we introduce two new highly-porous carbon
materials for assembling high specific area electrodes for IPMC actuators and compare their electromechanical
performance with recently reported IPMCs based on RuO<sub>2</sub> electrodes. We synthesize ionic liquid (Emi-Tf) actuators
with either Carbide-Derived Carbon (CDC) (derived from TiC) or coconut shell based activated carbon electrodes. The
carbon electrodes are applied onto ionic liquid-swollen Nafion membranes using the direct assembly process. Our results
show that actuators assembled with CDC electrodes have the greatest peak-to-peak strain output, reaching up to 20.4 mε
(equivalent to >2%) at a 2 V actuation signal, exceeding that of the RuO<sub>2</sub> electrodes by more than 100%. The electrodes
synthesized from TiC-derived carbon also revealed significantly higher maximum strain rate. The differences between
the materials are discussed in terms of molecular interactions and mechanisms upon actuation in the different electrodes.
Nafion is widely known as one of the most popular membrane materials for low temperature fuel cell applications.
However, the particular exchange membrane material properties make it also valuable for other applications. One of the
electroactive polymer (EAP) subclasses, ionic polymer metal composites (IPMC) commonly exploits Nafion as the ion
exchange polymer membrane. The ion conducting properties of Nafion are extremely important for IPMCs. Although,
ion conductivity depends strongly on the structural properties of the polymer matrix, there has been very little insight at
the atomistic level. Molecular dynamics simulations are one of the possibilities to study the ion conduction mechanism
at atomistic level. So far, the simulation results have been rather contradictory and very much dependent from the force
fields and polymer matrix setup used. In the present work, new force field parameters for Li<sup>+</sup> and Na<sup>+</sup> - nafion based on
DFT calculations are presented. The developed potentials and the force field were tested by molecular dynamics
simulations. It can be concluded that Li<sup>+</sup> and Na<sup>+</sup> ions are coordinated to different Nafion side-chain terminal group
(SO<sub>3</sub><sup>-</sup>) oxygens and to very few water molecules. One cation is coordinated to three different side-chains. Oxygens of
SO<sub>3</sub> groups and cations form complicated multi-header systems. In the equilibrium state, no cations dissociated from
side chains were found.
Molecular Dynamics (MD) techniques have been used to study the structure and dynamics of a model system of an
interpenetrating polymer (IPN) network for actuator devices. The systems simulated were generated using a Monte
Carlo-approach, and consisted of poly(ethylene oxide) (PEO) and poly(butadiene) (PB) in a 80-20 percent weight ratio
immersed into propylene carbonate (PC) solutions of LiClO<sub>4</sub>. The total polymer content was 32%, in order to model
experimental conditions. The dependence of LiClO<sub>4</sub> concentration in PC has been studied by studying five different
concentrations: 0.25, 0.5, 0.75, 1.0 and 1.25 M. After equilibration, local structural properties and dynamical features
such as phase separation, coordination, cluster stability and ion conductivity were studied. In an effort to study the
conduction processes more carefully, external electric fields of 1×10<sup>6</sup> V/m and 5×10<sup>6</sup> V/m has been applied to the
simulation boxes. A clear relationship between the degree of local phase separation and ion mobility is established. It is
also shown that although the ion pairing increases with concentration, there are still significantly more potential charge
carriers in the higher concentrated systems, while concentrations around 0.5-0.75 M of LiClO<sub>4</sub> in PC seem to be
favorable in terms of ion mobility. Furthermore, the anions exhibit higher conductivity than the cations, and there are
tendencies to solvent drag from the PC molecules.
Molecular Dynamics (MD) techniques have been used to study the structure and dynamics of hydrated Li- and Na-Nafion membranes. The membranes were generated using a Monte Carlo-approach for Nafion 117 oligomers of Mw = 1100 and with water contents of 7.5 and 20 % by weight, equivalent to 5 and 15 water molecules per sulfonate group, respectively. After equilibration, local structural properties and dynamical features such as coordination, cluster stability, solvation and ion conductivity were studied. In a comparison between the two cationic systems, it is shown that the Na-Nafion system is more sensitive than Li-Nafion to the level of hydration, and also show higher ion conductivity. The ionic conductivity is shown to increase with higher level of hydration.