Feasibility of Conducting Semi-Interpenetrating Networks Based on a Poly(ethylene oxide) Network and Poly(3,4- ethylenedioxythiophene) in Actuator Design F. Vidal, J.-F. Popp, C. Plesse, C. Chevrot, D. Teyssie ´ LPPI, Universite ´ de Cergy-Pontoise, 5 Mail Gay-Lussac, Neuville sur Oise, F-95031, Cergy-Pontoise Cedex, France Received 20 March 2002; accepted 16 April 2003 ABSTRACT: A new type of synthetic pathway—the use of interpenetrating polymer networks (IPNs)—is proposed to design conducting polymer-based actuators. Two types of materials with interesting conducting properties were pre- pared: (1) a semi-IPN between poly(3,4-ethylenedioxythio- phene) (PEDOT) and branched poly(ethylene oxide) (PEO) network; (2) a tricomponent IPN between PEDOT and a PEO/polycarbonate (PC)– based network as the ionic con- ducting partner. In the ﬁrst case, the inﬂuence of the amount of branching in the PEO network on the EDOT uptake and electrochemical properties was studied. A maximum con- ductivity (15 S cm -1 ) was obtained for 60 wt % branched PEO in the material. Moreover, the dispersion proﬁle of PEDOT in the material was shown by elemental analysis and energy dispersion spectroscopy to follow a gradient through the thickness of the ﬁlm leading to a built-in three- layered device. With respect to PEO/PC materials, the best results were obtained for about 80 wt % PEO in the matrix where the material remains sufﬁciently elastomeric. In this case, the conductivity reaches about 1 S cm -1 for a 10 to 30 wt % polycarbonate content. These materials are capable of reversible 45° angular deﬂections under a 0.5V potential difference. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3569 –3577, 2003 Key words: actuators; networks; conjugated polymers; in- terpenetrating networks (IPN); polycarbonates INTRODUCTION Conducting polymers are now considered a very im- portant class of materials showing interesting electri- cal and optical properties. However, it is well-known that several among these polymers are insoluble in common solvents and usually decompose before melt- ing. 1 In this case, the conventional methods of poly- mer processing cannot be used. Extensive studies have been carried out to overcome the poor processability of such compounds. On the other hand, conducting polymers seldom possess good mechanical properties. Two approaches have been widely investigated to obtain conducting materials with both good mechan- ical properties and good electronic conductivity (i.e., blends of conducting and insulating polymers, the latter being used for its mechanical properties as well as the preparation of conducting composites). 2 One possibly promising solution could be the combination of a conducting and an insulating polymer into inter- penetrating polymer networks (IPNs). IPNs are de- ﬁned as a combination of two or more polymer net- works necessarily synthesized in the presence of each other. 3,4 The presence of entangled crosslinks in- creases the miscibility of the polymers compared to usual blends and leads to a material with good dimen- sional stability. Semi-IPNs are the combination of at least one crosslinked polymer and one linear polymer. Speciﬁc noncovalent interactions between the linear and the crosslinked component can lead to a semi-IPN system where the linear polymer is deﬁnitely trapped in the structure although not covalently crosslinked. The aim of these types of polymer associations in general is to obtain materials (1) with better mechan- ical properties, (2) with dimensional stability, and (3) a possibly improved combination of the properties of its components. The synthesis of several electronic con- ducting semi-IPNs have been reported. 5–10 In most reported cases, the observed volume percolation threshold for conductivity (generally 5%) is lower than that observed in statistical blends (e.g., 16 vol %). Conducting polymers have also attracted consider- able attention notably because of possible dimensional changes generated by the expulsion/inclusion of ions during oxidation or reduction processes. 11–25 Con- ducting polymers thus can be used as the active ma- terial in actuators or artiﬁcial muscles and lead to interesting potential applications (robotics, prosthet- ics, microvalves, etc.). Among electronic conducting polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) has received much attention recently because of its particularly high stability in the doped state and the Correspondence to: D. Teyssie ´ (dominique.teyssie@chim.u- cergy.fr). Journal of Applied Polymer Science, Vol. 90, 3569 –3577 (2003) © 2003 Wiley Periodicals, Inc.