Synthesis of conductive particles based on PEDOT and processing of thermoplastic composites by extrusion

Les matériaux polymères conducteurs électriques font partie des matériaux polymères fonctionnels à haute valeur ajoutée pour de multiples applications émergentes, en particulier dans le domaine de l’électronique souple. De nombreuses applications industrielles intéressantes existent comme le chauffage par effet Joule ou l’isolation/blindage électromagnétique. A l’heure actuelle, cette dynamique s’étend au secteur de la plasturgie via les technologies émergentes de la fabrication additive et de la plastronique. Cependant, de nombreux verrous concernant les polymères conducteurs actuellement disponibles doivent être levés. Récemment, le PEDOT a permis d’atteindre des niveaux de conductivité électrique proche des métaux (env. 5000 S/cm). Cependant, le PEDOT est un polymère infusible et ne peut donc pas être mis en œuvre facilement par les techniques conventionnelles de l’industrie de la plasturgie. Pour contourner cet inconvénient, la stratégie mise en œuvre a été d’utiliser le PEDOT comme charge conductrice organique en le dispersant dans une matrice thermoplastique par extrusion pour obtenir des composites thermoplastiques conducteurs.Electrically conductive polymer materials are among the functional polymer materials with high added value for many emerging applications, particularly in the field of flexible electronics. There are many interesting industrial applications, such as Joule heating and electromagnetic insulation/shielding. This dynamic is now being extended to the plastics processing sector via the emerging technologies of additive manufacturing and plastronics. However, there are still a number of obstacles to be overcome when it comes to the conductive polymers currently available. Recently, PEDOT has made it possible to achieve electrical conductivity levels close to those of metals (around 5000 S/cm). However, PEDOT is an infusible polymer and cannot therefore be processed easily using conventional techniques in the plastics processing industry. To overcome this drawback, the strategy implemented was to use PEDOT as an organic conductive filler by dispersing it in a thermoplastic matrix using extrusion to obtain conductive thermoplastic composites

Synthesis of PEDOT particles and manufacturing of electrically-conductive PEO / PEDOT thermoplastic composites by twin-screw extrusion

International audienceThe electrical conductivity of thermoplastic composites made of poly(3,4-ethylenedioxythiophene) (PEDOT) particles and poly(ethylene oxide) (PEO) matrices is here investigated, in particular using a manufacturing process based on twin-screw extrusion. PEDOT particles without PSS were first synthesized by oxidative polymerization in an aqueous medium and characterized using various techniques (conductivity measurements, SEM, TGA, laser granulometry, XRD and XPS). The polymerization temperature of PEDOT particles was found to be a crucial factor. A maximal conductivity of 50 S.cm−1 was obtained when synthesized at ambient temperature. Relationships between the polymerization temperature and the structure of PEDOT particles were revealed and discussed. PEDOT particles were then incorporated up to 60 wt% into PEO matrix by twin-screw extrusion to manufacture electrically-conductive PEO/PEDOT thermoplastic composites. Their electrical conductivity increased with the PEDOT content and outstanding electrical conductivities up to 12 S.cm−1 were reached. The electrical percolation of this system was determined and discussed based on morphological studies by SEM and X-Ray tomography. The effect of PEDOT concentration on thermal properties of PEO matrices was also revealed by DSC. This work provides a novel approach for the manufacture of thermoplastic composites with high electrical conductivities using industrial technologies with multiple applicative perspectives, in particular into polymer-based electronics

Synthesis and characterization of PEDOT, an intrinsically conductive polymer

International audiencePoly(3,4-ethylenedioxythiophene) (PEDOT) is a highly valuable polymer material for modern electronics due to its impressive electrical conductivity (up to 1000 S.cm$^{−1}$). Combined with poly(styrenesulfonate) (PSS), PEDOT can beprocessed into thin film for a multitude of applications. However, the introduction of PEDOT in melt-state processes of the plastic industryis still challenging because PEDOT is infusible and only commercially available as highly diluted aqueous solutions. Nevertheless, previous study showed that extrusion processing of PEDOT:PSS solutions with PEO as a melting carrier is possiblebut sophisticated pre/post-treatments are mandatory to maintain high level of electrical conductivity up to 5 S.cm$^{−1}$.In this context, the goal of this study is to synthesize electrically conductive polymeric particles of PEDOT. An oxidative chemical polymerization of EDOT was carried out using two different oxidants: Fe$_2$(SO$_4$)$_3$ and FeCl$_3$. Resulting polymeric particles were studied thanks to SEM observations and resistivity measurements. The influence of parameters such as the ratio (monomer/oxidant), the polymerization time or the use of surfactants on the conductivity of PEDOT particles was studied.Interestingly, as-prepared PEDOT particles display conductivities between 0.1 and 10 S.cm$^{−1}$ without any posttreatment. This result is nearly 1000 times higher than previously reported by Jiang et al. A first explanation can be the presence of the oxidant/surfactant combined with PEDOT particles and acting as a dopant. Besides, comparison between the samples allows us to highlight the impact of the monomer-oxidant ratio on the electrical conductivity of the pellets. To better understand these results, correlations between (i) the polymerization process, (ii) the particles morphology and (iii) final electrical properties are currently being investigated