Frédéric Vidal

Dry Etching Process on a Conducting Interpenetrating Polymer Network Actuator for a Flapping Fly Micro Robot

In this paper we report on conducting polymer micro-actuators which have been fully patterned using photolithography and plasma dry etching processes. The interpenetrating polymer network (IPN) architecture used in this work resolves interface and adhesion problems which have been reported for traditional conducting polymer-based actuators. Actuator films 17 μm thick can be obtained and then patterned using microfabrication technologies. IPN-actuators were etched to obtain 2*5mm2 beams operating in air. These micro-sized actuators are potential candidates in numerous low frequency applications, including micro-valves, micro-optical instrumentation and micro-robotics. Moreover, due to the rapid response of our IPN architecture, this material has been considered as the main actuator for the flapping wings of an artificial insect.Copyright

Actuator based on poly(3,4-ethylenedioxythiophene)/PEO/elastomer IPNs

In order to solve the interface and adhesion problems encountered with multilayered actuators, IPN based actuators are presented. The IPNs are synthesized between poly(ethylene oxide) and polybutadiene networks in which the conducting polymer (poly(3,4-ethylenedioxythiophene)), PEDOT, is gradually dispersed i.e. the content decreases from the outside towards the center of the film. The conducting IPN morphology was investigated by DMA and microscopy. The choice of the solid polymer electrolyte system is critical when operating in air. Aqueous solution or organic solvents containing electrolytes were first used, but drying failure could not be prevented. The most promising results are obtained with a room temperature ionic liquid, 1-ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)imide (EMITFSI). During the redox reactions involving PEDOT in EMITFSI, a cation transfer mechanism occurred. Moreover, the bis-(trifluoromethylsulfonyl)imide anion behaves as a plasticizing agent for the IPN matrix. We observed that no degradation of the conducting polymer and no drying process occurred during period as long as 3 months. These actuators can achieve more than 7 E6 bendings from 1 to 18 Hz under applied potential from 2 to 5 V

Actuators based on conducting poly(3,4-ethylenedioxythiophene)/PEO semi-IPN

A new approach is proposed, namely the use of Interpenetrating Polymer Networks (IPNs) in order to solve the interface and adhesion problems in the design of classical conducting polymer based actuators. Semi IPN type materials are synthesized between poly(3,4-ethylenedioxythiophene) and a poly(ethyleneoxide) based network as the ionic conducting partner. The synthetic pathway which will be presented ensures a gradual dispersion of the electronic conducting polymer through the thickness of the material i.e. the content decreases from the outside towards the center of the film. The system is thus similar to a layered one with the advantage that the intimate combination of the two polymers needs no adhesive interface. The influence of the morphology and chemical composition of the matrix on the electronic conductivity of the material have been studied. The surface conductivity can reach 15 S/cm. Finally, this material is capable of a 45 degree(s) angular deflexion under a 0.5 V potential difference.

Polysiloxane Based Interpenetrating Polymer Networks: synthesis and Properties

This article summarizes a large amount of work carried out in our laboratory on polysiloxane based Interpenetrating Polymer Networks (IPNs). First, a polydimethylsiloxane (PDMS) network has been combined with a cellulose acetate butyrate (CAB) network in order to improve its mechanical properties. Second, a PDMS network was combined with a fluorinated polymer network. Thanks to a perfect control of the respective rates of formation of each network it has been possible to avoid polymer phase separation during the IPN synthesis. Physico-chemical analyses of these materials led to classify them as “true” IPNs according to Sperling’s definition. In addition, synergy of the mechanical properties, on the one hand, and of the surface properties, on the other hand, was displayed.

Conducting IPNs and Ionic Liquids: Applications to Electroactive Polymer Devices

The synthesis of interpenetrating polymer networks (IPNs) is proposed as an alternative to polyether-based (co)polymers or networks for the design of solid polymer electrolytes (SPEs). IPNs were prepared from an elastomer bringing the mechanical properties and poly(ethylene oxide). These IPNs, swollen by N-ethylmethylimidazolium bis(trifluoromethanesulfonyl)-imide (EMITFSI), possess an ionic conductivity close to 10−3 S cm−1 at 30 °C. In order to form conducting IPNs, chemical polymerization of 3,4-ethylenedioxythiophene (EDOT) has been carried out within the SPE IPN. A pseudo-trilayer configuration has been obtained with the SPE IPN sandwiched between two interpenetrated PEDOT electrodes. Controlling the PEDOT content from 0.3 to 24 wt% in the material, electrochromic, electroreflective, or electromechanical devices is obtained.

Toward electroactive catheter design using conducting interpenetrating polymer networks actuators

Several studies have been reported on the development of controllable catheters in the biomedical field. Electronic conductive polymers (ECP) actuators appeared to be among the most suitable systems thank to their biocompatibility, low operating potential (± 2V) with a reasonable deformation (2%)[1–3]. Electroactive catheters, especially in neurosurgery, should have two levels of properties: strong deformations tip in order to reach, for example the aneurysms and sweep the total volume of the pouch, and sufficient rigid middle part for getting forward in the tortuous vessels network. We designed an electroactive catheter, constituted of two parts with different deformation ability and modulus. The high deformations tip can be obtained with a weak modulus actuator. On the other hand, the second part needs to possess high modulus where small deformations are sufficient. In this work, interpenetrating polymer networks (IPN) will be used as the structural material of the catheter. The IPN architecture allows the synthesis of actuators containing the ions necessary for the redox process and thus avoiding any interference of the position control due to the exchange with the ions from the physiological medium. In addition, the fact that the catheter can be synthesized in a customized way allows modulating its mechanical properties. By introducing a rigid polystyrene network into a specific part of the actuator, it is possible to locally increase the rigidity of the device while keeping reasonable deformation. First, we will describe the synthesis and the characterization of a beam shape actuators with different local stiffnesses. Then, the first steps for the elaboration of tubular actuator will be presented.

All-solid state ionic actuators based on polymeric ionic liquids and electronic conducting polymers

Ionic electro-active polymers (EAP) are promising materials for actuation and sensing. In order to operate in open-air, they are usually built in a trilayer configuration where the internal polymer membrane is soaked with an exogenous electrolyte and sandwiched between two electronic conducting polymer (ECP) layers. The use of exogenous electrolytes can be a limitation in several applications since it may lead to evaporation issues and leakage. Moreover, the soaking step, necessary to introduce the electrolyte in the device, can become tricky as soon as microdevices are considered. In this work we describe the synthesis and characterization of truly “all-solid-state” ionic actuators by using polymeric ionic liquids (PILs). PILs are a new class of polyelectrolytes presenting ionic liquid-like ions along their polymer backbone. First, ECP electrodes containing PIL are synthesized by vapor phase polymerization and their thickness and electronic conductivity are characterized. Then, electrodes and PIL-based membranes are assembled into a trilayer configuration as a proof of concept of solid-state ionic actuator. Under 1.75V, a strain difference about 1% is reached.