Conducting films applications

The electrochemistry of conducting polymers has been the subject of several reviews2-8 and has been included in articles on chemically modified electrodes.9-14 The primary purpose of this chapter is to review fundamental aspects of the electrochemistry of conducting polymer films. Applications, the diversity of materials available, and synthetic methods are not covered in any detail. No attempt has been made at a comprehensive coverage of the relevant literature and the materials that have been studied. Specific examples have been selected to illustrate general principles, and so it can often be assumed that other materials will behave similarly. 

It was also observed that, with the exception of polyacetylene, all important conducting polymers can be electrochemically produced by anodic oxidation moreover, in contrast to chemical methoconducting films are formed directly on the electrode. This stimulated research teams in the field of electrochemistry to study the electrosynthesis of these materials. Most recently, new fields of application, ranging from anti-corrosives through modified electrodes to microelectronic devices, have aroused electrochemists interest in this class of compounds... 

The above-mentioned method is effective in identifying the molecules of detected ions. However, because PVDF film is not permeable to light, it is difficult to observe tissue sections. To resolve this problem, we developed a method to fix tissue sections on transparent film, and then performed MS on those sections.6 We used a conductive film because we expected the ionization efficiency would increase when the electric charge accumulation on the sample was reduced. The film used for this purpose was a polyethylene terephthalate (PET) film with a thickness of 75-125 pm, having a 5 15-nm-thick layer of evaporated oxidation indium tin (ITO) upon it (ITO film). This film is used in touch-panel displays because of its high transparency and superior conductivity. We used it to perform MS/MS for tissue sections and succeeded in identifying multiple proteins from mass spectra.6 Therefore, the further development of this method will enable the application of the mass-microscopic method to observe tissue by optical microscope and to perform tandem mass spectrometry (MSn) at the observation part, simultaneously, enabling the identification of molecules included the part. 

Shimma S, Sugiura Y, Setou M. Applications of conductive film as a sample support material for direct tissue mass spectrometry (WP336). I Mass. Spectrom. Soc. Jpn. 2006 54 210-211. 

Polythiophenes (PTs)/CNTs composites have emerged as an intriguing system for use as photovoltaic devices and field effect transistors [57]. Swager and Bao independently reported methods for the assembling of PTs/CNTs systems and showed their great potential as transparent conductive films [58]. Another interesting application arises from the possibility to functionalize the polythiophene backbone for applications as chemical sensors [134]. 

While dicarboxylic acid-functional pyrroles have received only cursory attention in condensation polymerizations, other derivatives have been studied extensively. Pyrrole itself has been electrooxidatively polymerized (81CS145) to give a flexible conductive film, presumably containing poly(2,5-pyrrolediyl) units (23) as the main structural feature. The blue-black polymer obviously contains other functionality, as evidenced by elemental analysis and by the fact that it carries a partial positive charge, and it exhibits p-type conductivities approaching the metallic range (e.g. 100 fi-1 cm-1). The main utility of poly(pyrrole) (23) has been for the modification of electrode surfaces, although numerous other applications can be envisioned. 

PVF resins have also been used in a variety of other applications, includ ing conductive films, electrophotographic binders, as a component for inks and in membranes, pholoimaging, solder masks, and reprographic loners. 

Concerning the application of gallium alkoxides, one can mention the selective catalytic activity of Ga(OPh)3in the condensation reactions of isobutene with phenols. In(OR)3 is used for the preparation of solutions for production of ln203 and In2Oj-related conduction films [1618] and also in the synthesis of volatile precursors for MOCVD deposition of In2Oj [830]. 

The obtaining of tin(IV) alkoxides was first reported in a well-known publication by Meerwein and Bersin [1101] devoted to bimetallic alkoxides. At the end of the 1950s Bradley [222] and Make [1049] practically simultaneously devoted the synthetic approaches to and described the properties of nearly all major representatives of the Sn(OR)4homologous series. During the last 10 to 20 years interest in these compounds was renewed due to the prospect of their application in the synthesis of optically transparent and conducting films based on Sn02, and also of related ceramic materials. The alkoxides of Sn(IV) were considered in detail in a review by Hampden-Smith etal. [702],... 

Comparable to thiophene, pyrrole is a five-membered heterocycle, yet the ring nitrogen results in a molecule with distinctly different behavior and a far greater tendency to polymerize oxidatively. The first report of the synthesis of polypyrrole (PPy) 62 that alluded to its electrically conductive nature was published in 1968 [263]. This early material was obtained via electrochemical polymerization and was carried out in 0.1 N sulfuric acid to produce a black film. Since then, a number of improvements, which have resulted from in-depth solvent and electrolyte studies, have made the electrochemical synthesis of PPy the most widely employed method [264-266]. The properties of electrosynthesized PPy are quite sensitive to the electrochemical environment in which it is obtained. The use of various electrolytes yield materials with pronounced differences in conductivity, film morphology, and overall performance [267-270]. Furthermore, the water solubility of pyrrole allows aqueous electrochemistry [271], which is of prime importance for biological applications [272]. 

A final point should be made concerning the single-wafer CVD reactor concept. This approach only makes sense if each wafer can be processed in 1 to 2 minutes, so reasonable throughput can be achieved. In many applications, conducting films can be thin, 2000 A, so deposition rates of 1000 to 1500 A/min would be suitable. Such rates are not unreasonable, for example, for WSi2 films. 

For anodic processes the choice of materials for the electrode is much more limited than for cathodic ones, as the anode could bo easily attacked by the products of the electrolysis (chlorine, oxygon etc.), or electrochemioally dissolved. In alkaline solutions the selection will be restricted to the application of platinum (or alloys of platinum with irridium or rhodium), palladium, carbon (or rather graphite) iron and nickel, while for acid solutions only metals of the platinum group and graphite will be suitable in a special case of the electrolysis in sulphuric acid solutions lead has found wide use, it getting coated with a conductive film of lead dioxide. 

Organic conductive films, e.g. polyaniline or polythiophene, have an interesting potential application due to their easy processability combined with a low weight. A plasma deposition process is even more interesting from a technical point of view, because it is, as opposed to wet chemistry, much more compatible with production processes in vacuum. The sample used was polymerized by Kruse et al. [454] on a silicon wafer over 20 min in a microwave plasma chamber at 2.45 GHz using 2-iodothiophene (at... 

Substituted CPs were initially prepared to achieve processibility they are even less well organized. Many such CPs can be cast into homogeneous films, extrusion molded, drawn into fibers, and therefore oriented. In all these shapes they are generally dopable to sufficiently high conductivity for applications. Attempts to prepare various types of composites have begun. 

In this chapter we reviewed our work on preparing ion conductive films by using DNA. The highest ionic conductivity of 5.05 x 10 S cm was found to be at 50°C when 93 wt% EImBF4 is mixed with DNA neutralized with HBF4. The DNA film was obtained by casting a DNA aqueous solution. The attractive characteristics of DNA is that it is a biodegradable material that has an inexhaustible supply in nature. We showed in this chapter that several properties, such as ionic conductivity of DNA films, can be controlled by certain factors. It is our hope that our results well open the way to new applications of DNA. 

Tin doped ln203 (ITO) films, widely used in photonic devices, are prepared by sputtering [122-127], The sputtering technique requires sufficiently dense targets without any additives for highly conductive films [128-130], Due to low sinterabiliry of ITO [131,132], however, a costly hot-pressing procedure is often necessary. Another application of soft mechanochemistry where dissolution reprecipitation is involved was proposed [133],... 

Copper Conductive films semiconductor devices. Gold Metallization of contacts in semiconductor applications. 

Numerous other fields of diamond film application are known, and more are sure to emerge in the future. One potential application makes use of the diamond films high thermal conductivity, which by far exceeds that of any other bulk material. Hence, diamond is suitable for heat dissipation, for example, in electronic circuitry. For instance, a surface may be coated with a layer of CVD diamond which then effects the removal of heat Another conceivable setup would be using a... 

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