Polymers electrochemical applications

Here we introduce a personal point of view about the interactions between conducting polymers and electrochemistry their synthesis, electrochemical properties, and electrochemical applications. Conducting polymers are new materials that were developed in the late 1970s as intrinsically electronic conductors at the molecular level. Ideal monodimensional chains of poly acetylene, polypyrrole, polythiophene, etc. can be seen in Fig. 1. One of the most fascinating aspects of these polymeric... 

Carbon is unique among chemical elements since it exists in different forms and microtextures transforming it into a very attractive material that is widely used in a broad range of electrochemical applications. Carbon exists in various allotropic forms due to its valency, with the most well-known being carbon black, diamond, fullerenes, graphene and carbon nanotubes. This review is divided into four sections. In the first two sections the structure, electronic and electrochemical properties of carbon are presented along with their applications. The last two sections deal with the use of carbon in polymer electrolyte fuel cells (PEFCs) as catalyst support and oxygen reduction reaction (ORR) electrocatalyst. 

Another conducting polymer of interest for electrochemical applications is polyaniline ... 

The resorcinol-formaldehyde polymers have been used to prepare highly porous carbon materials, by controlled pyrolysis in an inert atmosphere [144,154], The microstructure of the carbon is an exact copy of the porous polymer precursor. Poly(methacrylonitrile) (PM AN) PolyHIPE polymers have also been used for this purpose. These monolithic, highly porous carbons are potentially useful in electrochemical applications, particularly re-chargeable batteries and super-capacitors. The RF materials, with their very high surface areas, are particularly attractive for the latter systems. 

In the case of ion conductive polymers, gel polymer electrolytes which consist of a polymer matrix, organic solvents and supporting electrolyte, were introduced as novel nonaqueous electrolyte systems in electrochemical applications, such as rechargeable batteries and electric double layer capacitors [3-5], Recently, considerable attention has been devoted to the application of gel poly-... 

Mixed polymers containing thiophene moieties are of considerable interest for electrochemical applications because by this approach both physical and chemical properties can be fine-tuned in a very delicate fashion. 

Electrochemistry in RTILs has recently been reviewed, and a book has been published on the topic. a large number of metals have been deposited from ionic liquids (Table 6.5) and a book has also been published on electrodeposition from these media. Alloys, semiconductors and conducting polymers have also been deposited from ionic liquids. The key advantages of ionic liquids for electrodeposition and electrochemical applications are their wide potential window, the high solubility of metal salts, the avoidance of water and their high conductivity compared to non-aqueous solvents. There are numerous parameters that can be varied to alter the deposition characteristics including temperature, the cation and anion used, diluents and additional electrolytes. ... 

As one looks back over the last few decades it is possible to see trends emerging in the ionic liquids that are used and the main foci of interest. Early chloroaluminate systems with potential electrochemical applications gave way to ionic liquids with more air stable anions, with interest moving on to chemicals synthesis and catalysis. Then came new systems with specific properties to use as Task Specific Ionic Liquids (see Chapter 3), or for dissolving biomass polymers (Chapter 10), or as engineering fluids of various types. A small number of papers have now appeared on mixtures of ionic liquids. The exciting thing about ionic liquids is that as each development has occurred it has been in addition to the previous activities and not a replacement for these. 

The work was supported by the Ministry of Science and Technological Development of the Republic of Serbia under the research projects Deposition of ultrafine powders of metals and alloys and nanostructured surfaces by electrochemical techniques (No. 142032G) and Modification of metal and nonmetal materials by electroconductive polymer for application in new technologies (No. 142044). 

Potential applications of perfluorinated carboxylate membranes have been focused to date on the chlor-alkali process. It has been pointed out previously that these polymers in acid form are not desirable for electrochemical applications because of rather high resistance. ... 

In scientific terms, the unusual ion-clustered morphology of the perfluorinated ionomer polymers has provoked much interest. Clearly, the microphase-separated structure that is revealed through various types of experiments is strongly related to their unusual transport properties. It is important to refine our understanding of this relationship in order to exploit these materials in various electrochemical applications. 

Flemion is quite different from prior membranes in that it is based on specific perfluorinated copolymers with pendant carboxylic acid as a functional group. The introduction of carboxylic functions in the polymer has realized high permselectivity in cation transport with high conductivity, which is indispensable to electrochemical application of ion exchange membranes. 

Supramolecular complexes based on these polymers have applications not only in sensing based on the electrochemical response [86,87], but also utilizing changes in the emission properties [88]. A new absorbance band appeared after Zn binding to polymer 43, and the emission was weaker and red shifted. Interestingly, exposure of the Zn-substituted polymers to alcohol vapor resulted in a restoration of the emission intensity. 

Solid state materials that exhibit high ion transport properties are of interest from both academic as well as applied points of view. Polymer solid electrolytes are materials of high technological promise in several electrochemical applications such as high energy density batteries, gas sensors, electrochemical devices etc. These polymeric materials have attracted much attention and hold great promise in this area. 

Nafion polymers have been developed recently by the du Pont Company. They are perfluorosulfonic acid membranes mainly used as separators in electrochemical applications. The backbone of the poljrmer chains consists of perfluoroethylene units whereas the side chains are of the form - 0 - CF2 - CF... 

Since the applications of conducting polymers are detailed in Chapters 1-7 we only mention briefly the general principles involved in electrochemical applications with some examples cited. More applications were made for PPy films than any other -conjugated polymers. This is because PPy is easier to prepare under ambient experimental conditions in both aqueous and non-aqueous solutions. It is rather straightforward to incorporate foreign materials such as enzymes without harming their integrity. For this and many other reasons, an extensive number of papers have been published in this area. Even for PAn alone, the applications are too many to discuss in detail and, thus, we summarize electrochemical applications known for PAn only. For other polymers, similar... 

While PAn and PPy found numerous electrochemical applications due to more friendly environments in which many chemical, as well as biological molecules, can be introduced into the matrices of these polymers, PA does not find as many applications because it is prepared in a more hostile environment for these molecules. For this reason, only properties such as conductivities and electroactivities can be taken advantage of for applications. Since both the neutral and oxidized/reduced PA is not stable in air, it can be used only in rigorously de-aerated environments. 

The monomer XXVIII is copolymerized with tetralluoroethylene to give a polymer-containing pendant fluorosulfonyl groups that are then hydrolyzed and acid exchanged to produce Nafion (XXIX) The resulting polymer combines the chemical, thermal, and oxidative stability of perfluorinated polymers such as polytetra-fluoroethy lene with the properties ofahighly acidic fluorinated sulfonic acid. Nafion is used in a variety of electrochemical applications such as the synthesis of chlorine and caustic and as the conductive membrane of many modern fuel cells. It has also been used in water electrolysis and as an acid catalyst in many proprietary commercial processes. 

Pei Q, Inganas O (1993) Electrochemical applications of the bending beam method, a novel way to study ion-transport in electroactive polymers. Solid State Ion 60 161... 

---