Jason W. Paquette

Ionomeric electroactive polymer artificial muscle for naval applications

Specialized propulsors for naval applications have numerous opportunities in terms of research, design, and fabrication of an appropriate propulsor. One of the most important components of any propulsor is the actuator that provides the mode of locomotion. ionomeric electroactive polymer may offer an attractive solution for locomotion of small propulsors. A common ionomeric electroactive polymer, ionic polymer-metal composites (IPMCs) give large true bending deformations under low driving voltages, operate in aqueous environments, are capable of transduction, and are relatively well understood. IPMC fabrication and operation are presented to further elucidate the use of the material for a propulsor. Various materials, including IPMCs, are investigated and a simplified propulsor model is explored.

An Equivalent Circuit Model for Ionic Polymer-Metal Composites and their Performance Improvement by a Clay-Based Polymer Nano-Composite Technique

Ionic Polymer-Metal Composite (IPMC) is a new class of polymeric material exhibiting large strain with inherent soft actuation. The observed motion characteristics of an IPMC subjected to an electric field is highly nonlinear. This is believed to be due primarily to the particle electrodes on the IPMC surface, which is inherently both capacitive and resistive due to particle separation and density. Knowing that the value of resistivity and capacity can be manipulated by the number of metal platings applied to the IPMC, the force response of an IPMC when subjected to an imposed electric field is due to the interaction of an array of capacitors and resistors along with ionic migration. In this effort we attempt to incorporate a capacitive and resistive model into the linear irreversible thermodynamic model. The advantages of using such a model are (i) the possible dynamic predictability of the material itself in connection with capacitive responses; and (ii) the realization of capacitive and resistive effect arising from the particle electrodes and the base polymer, respectively. The behavior of the proposed model can explain typical experimentally obtained values well. Also, an experimental effort to improve the properties of the base polymer was carried out by a novel nanocomposite technique. The experiment results on the current/voltage (I/V) curves indicate that the starting material of ionic polymer-metal composites (IPMCs) can be optimized to create effective polymer actuators.

Ionic Polymer-metal Composites for Underwater Operation:

The ionic polymer-metal composite (IPMC) for flexible hydrodynamic propulsor blades can provide many new opportunities in navy platforms, especially in unmanned, robotic vehicles used in surveillance and combat. When in operation, the IPMC materials are very quiet since they have no vibration causing components, i.e., gears, motors, shafts, etc. For small autonomous underwater vehicles (AUV), this feature is truly attractive. IPMCs are friendly to solid-state electronics and have digital programming capabilities; thus, active control is possible. Another advantage of these materials is that they can be operational in a self-oscillatory manner. However, there are several issues that still need to be addressed: propulsor design, testing, robotic control, and the theoretical modeling of the appropriate design. Currently, the IPMC is being investigated for propulsor blade applications and a propulsor model with a robust control scheme. An analytical model of a segmented IPMC propulsor was formulated to be a building block for accommodating the relaxation behavior of IPMCs and for describing the dynamics of the flexible IPMC bending actuator.

The behavior of ionic polymer-metal composites in a multi-layer configuration

It has been observed that an ionic polymer?metal composite (IPMC) is both inherently resistive and capacitive. This allows for the material to be modeled using an equivalent RC circuit to describe the charging/discharging behavior associated with the IPMC. Typically, the model includes two resistors and two capacitors, which will primarily account for the effective electrodes on the surface of the IPMC (top and bottom). There will also be a resistor placed between the two RC circuits to account for material between the electrodes and the resistance due to ion migration through the polymer matrix. In this paper we report our recent effort to extend such a model to accommodate a multi-layer IPMC as well as inter-digitated electrodes. As expected, the observed electric characteristics of an IPMC subjected to an electric field are highly non-linear. This is believed to be due primarily to the particle electrodes on the IPMC surface, which is inherently both capacitive and resistive due to particle separation and density. The advantage of using such a model is to realize the capacitive and resistive effects and use them for a multi-layer configuration. We also present typical experimental data.

Operation of ionic polymer-metal composites in water

The Ionic Polymer-Metal Composite (IPMC) for flexible hydrodynamic propulsor blades can provide many new opportunities in the naval platforms, especially in developing robotic unmanned vehicles for both surveillance and combat. IPMC materials are quietly operational since they have no vibration causing components, i.e. gears, motors, shafts, and etc. For small Autonomous Underwater Vehicles (AUV), these features are truly attractive due to limited space. Also, IPMCs are friendly to solid-state electronics with digital programming capabilities. Active control is thus possible. Another advantage of these materials should be recognized from the fact that they can be operational in a self-oscillatory manner. There are several issues that still need to be addressed such as propulsor design, testing, robotic control as well as theoretical modeling of the appropriate design. In this effort, IPMC is investigated for propulsor blades applications in NaCl solution and a propulsor model with a robust control scheme is explored. An analytical model of a segmented IPMC propulsor was formulated to be used as a building block for furthering the model to adequately accommodate the relaxation behavior of IPMCs and for describing the dynamics of the flexible IPMC bending actuator.

Development of electroactive silicate nanocomposites prepared for use as ionic polymer-metal composites (IPMCs) artificial muscles and sensors

Nanocomposites are a new class of composites which are typically nanoparticle-filled polymers. One promising kind of nanocomposite is clay-based and polymer-layered silicates nanocomposites because the starting clay materials are naturally abundant and, also, their intercalation chemistry is well understood at the present time. A certain clay, Montmorillonite (MxAl4- xMgx)Si8O20

Aquatic robotic propulsor using ionic polymer-metal composite artificial muscle

(OH4 has two-dimensional layers of their crystal structure lattice where the layer thickness is around 1 nm with the lateral dimension of approximately 30 nm to a few microns. These layers organize themselves to form stacks, so-called the Gallery through a van der Walls gap in between them. In this work, Montmorillonite (MMT) was modified by a cationic surfactant so as to lower its surface energy significantly. Such a process gave rise to favorable intercalation of nanoparticles within the galleries. The obtained XRD patterns and TEM images indicate that the silicate layers are completely and uniformly dispersed (nearly exfoliated) in a continuous polymer matrix of Nafion that has been successfully used as a starting material of ionic polymer-metal composites (IPMCs).

Behavior of Ionic Polymer-Metal Composites Under Subzero Temperature Conditions

In this investigation, ionic polymer metal composites (IPMC) are considered for use as a means of aquatic propulsion. A simple propulsor is constructed to show capabilities of using an IPMC actuator. The thrust produced by the propulsor was recorded and reported showing suitable thrust for small applications. IPMC were then compared with competing electro-active polymers in a theoretical propulsor study showing that IPMC are quite competitive with similar actuator materials. An equivalent circuit to model the force behavior of an IPMC can be used to explain force behavior for various geometric configurations of IPMC leading the way for design and use of IPMC aquatic propulsors.

An Equivalent Circuit Model for Ionic Polymer-Metal Composites and Their Performance Improvement by a Clay-Based Polymer Nano-Composite Technique

Actuators that can operate within harsh environments, such as that of cold regions or outer space, could be quite useful. We have found that Ionic Polymer-Metal Composites (IPMCs) provide an attractive solution for cold operation actuators. This is because of their capability for soft actuation with relatively low voltages (1 to 5 V), durability and capability of operating within the subzero regime T < °C. The building block material of IPMCs, which is dependent upon hydration or weak chemical bonding by a solvent (typically water), experiences phase changes within the base material that results in an alteration of the performance of the material in terms of actuator performance. This alteration is to be expected, but the magnitude and degree of deviation from the actuation at normal room temperature are values of interest. An experimental apparatus is consructed in order to have a controlled temperature environment in which to analyze the material. The overall temperature within the reservoir, the temperature on the IPMC surface electrodes, the conductivity of the membrane and the blocking force were all measured and documented. The phase changes inherent at these low temperatures are investigated further by means of Differential Scanning Calorimeter to obtain the phase change temperatures. The electrical conductivity of the material was then used to help explain the phenomena for the overall change in behavior primarily at these phase change temperatures. The results are presented and interpreted to show that there is definite promise for these low temperature polymeric actuators to operate in practical applications. Also, some theoretical consideration is presented.Copyright

Ionic Polymer-Metal Composites as Smart Materials under Subzero Temperature Conditions

Ionic Polymer-Metal Composite (IPMC) is a new class of polymeric material exhibiting large strain with inherent soft actuation. The observed motion characteristics of an IPMC subjected to an electric field is highly non-linear. This is believed to be due primarily to the particle electrodes on the IPMC surface, which is inherently both capacitive and resistive due to particle separation and density. Knowing that the value of resistivity and capacity can be manipulated by the number of metal platings applied to the IPMC, the force response of an IPMC when subjected to an imposed electric field is due to the interaction of an array of capacitors and resistors along with ionic migration. In this effort we attempt to incorporate a capacitive and resistive model into the previously developed linear irreversible thermodynamic model. The advantages of using such a model are i) the possible dynamic predictability of the material itself; and ii) the realization of capacitive and resistive effect arising from the particle electrodes and the base polymer, respectively. The behavior of the proposed model can explain typical experimentally obtained values well. Also, an experimental effort to improve the properties of the base polymer was carried out by a novel nanocomposite technique. The experiment results on the current/voltage (I/V) curves indicate that the starting material of ionic polymer-metal composites (IPMCs) can be optimized to create effective polymer actuators.Copyright