Conducting Polymer Dispersions

To further simplify the manufacturing process and to replace the electrolytic or in situ polymerization completely, a nanoscale conducting polymer PEDOTPSS dispersions for the formation of the cathode layer within the porous stmcture of electrolytic capacitors was developed. This cathode layer formation is much more challenging than the build up of the outer polymer layer The electrical conductivity of the dispersion has to be very high and the dispersion must be capable to impregnate highly porous anode structures. 

The manufacturing of polymer electrolyte capacitors is facilitated significantly by PEDOTPSS dispersions because all process steps of the chemical or electrochemical polymerization can be substituted by simple coating steps. Since no chemical polymerization takes place during the manufacturing process of the capacitor, the process is easier to control and there are no side products like iron salts, which have to be washed out or which could deteriorate the performance in the finished product. Furthermore, waterborne 

Outer polymer layer made by a PEDOT PSS formulation on a tantalum capacitor body (layer position is indicated by the arrow). 

Particle size distribution of PEDOT PSS dispersion (mean particle size 30 nm) used for electrolytic capacitors. 

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Conductive polymer dispersions are these structured like microemulsions ... 

Expressions for the Flux j and Mechanistic Indicators for Microheterogeneous Catalysis at Conducting Polymer/Dispersed Microparticle Composite Systems... 

The formation of a conductive polymer cathode in electrolytic capacitors is hindered by the porous structure of the anode, especially for modern materials with very fine pores. In situ polymerization or the deposition of conducting polymer dispersions have to be applied for the formation of the polymer cathode since high performance conducting polymers are not soluble. 

Until a few years ago it was not possible to realize high capacitance and low ESR solid electrolyte capacitors with conductive polymer dispersions. Therefore, today, in situ polymerization is mainly used for conductive polymer processing in electrolytic capacitors. In situ polymerization can either be conducted by electrolytic oxidation or by chemical oxidation. 

Conducting Polymer Dispersion In Situ Polymerization without Reformation In Situ Polymerization with 50 V Reformation In Situ Polymerization with 75 V Reformation... 

U. Merker, K. Wussow, and W. Lovenich. 2005. New conducting polymer dispersions for solid electrolyte capacitors. In Proceedings of the 19th Passive Components Symposium CARTS Europe, 30-35. Prague, Electronic Components, Assemblies Materials Association. 

Bicomponent technology has been used to introduce functional and novelty effects other than stretch to nylon fibers. For instance, antistatic yams are made by spinning a conductive carbon-black polymer dispersion as a core with a sheath of nylon (188) and as a side-by-side configuration (189). At 0.1—1.0% implants, these conductive filaments give durable static resistance to nylon carpets without interfering with dye coloration. Conductive materials such as carbon black or metals as a sheath around a core of nylon interfere with color, especially light shades. 

Conducting Polymer Blends, Composites, and Colloids. Incorporation of conducting polymers into multicomponent systems allows the preparation of materials that are electroactive and also possess specific properties contributed by the other components. Dispersion of a conducting polymer into an insulating matrix can be accompHshed as either a miscible or phase-separated blend, a heterogeneous composite, or a coUoidaHy dispersed latex. When the conductor is present in sufftcientiy high composition, electron transport is possible. 

CNT films are also of interest from morphological aspect because their structure provides nanoscale voids within the networks of CNTs. For example, composites with conducting polymers are very interesting both from scientific and technological interests, since we would expect CNTs to give a well-dispersed film. 

Another convenient way to disperse platinum-based electrocatalysts is to use electron-conducting polymers, such as polyaniline (PAni) or polypyrrole (PPy), which play the role of a three-dimensional electrode.In such a way very dispersed electrocatalysts are obtained, with particle sizes on the order of a few nanometers, leading to a very high activity for the oxidation of methanol (Fig. 10). 

Incorporation into a Polymer Layer In recent years a new electrode type is investigated which represents a layer of conducting polymer (such as polyaniline) into which a metal catalyst is incorporated by chemical or electrochemical deposition. In some cases the specific catalytic activity of the platinum crystallites incorporated into the polymer layer was found to be higher than that of ordinary dispersed platinum, probably because of special structural features of the platinum crystallites produced within the polymer matrix. A variant of this approach is that of incorporating the disperse catalyst directly into the surface layer of a solid polymer electrolyte. 

Note 6 Electric conductance of a nonconducting polymer can be achieved by dispersing conducting particles (e.g., metal, carbon black) in the polymer. The resulting materials are referred to as conducting polymer composites or solid polymer-electrolyte composites. 

Transition metal compounds, such as organic macrocycles, are known to be good electrocatalysts for oxygen reduction. Furthermore, they are inactive for alcohol oxidation. Different phthalocyanines and porphyrins of iron and cobalt were thus dispersed in an electron-conducting polymer (polyaniline, polypyrrole) acting as a conducting matrix, either in the form of a tetrasulfonated counter anion or linked to... 

Electrically conducting polymer particles such as polypyrrole and polyaniline could also be prepared by dispersion polymerization in aqueous ethanol (31). The oxidation polymerization of pyrrole and aniline has been carried out at the electrode surfaces so far and formed a thin film of conducting polymer. On the other hand, polypyrrole precipitates as particles when an oxidizing reagent is added to a pyrrole dissolved ethanol solution, which contains a water-soluble stabilizer. In this way electrically conducting polymer particles are obtained and, in order to add more function to them, incorporation of functional groups, such as aldehyde to the surface, and silicone treatment were invented (32). 

The photoconductivity and absorption spectra of the multilayer polydiacetylene are shown in Fig. 22 [150]. The continuous and dotted line relate to the blue and red polymer forms respectively. Interpretation is given in terms of a valence to conduction band transition which is buried under the vibronic sidebands of the dominant exciton transition. The associated absorption coefficient follows a law which indicates either an indirect transition or a direct transition between non-parabolic bands. The gap energies are 2.5 eV and 2.6 eV for the two different forms. The transition is three dimensional indicating finite valence and conduction band dispersion in the direction perpendicular to the polymer chain. 

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