Electrically sensitive polymers applications

Polyacetylenc is the simplest and most studied conductive polymer which can be produced by polymerization of acetylene or by thermal treatment of a precursor polymer. Although its red sensitivity due to its band gap of 1.5 eV is ideal for photo-voltaic applications, many workers have to shift their interest to other systems, due to its instability. However, with all its drawbacks and with the development of newer and newer methods of stabilization of conductive polymers, it is still fascinating many researchers due to its useful electrical and electronic applications [4,66-68]. Studies of the oxidation of Shirakawa polyacetylene have been reviewed by Chien [10] and Pochan [52]. 

The pseudocapacitance can also be provided by other pseudocapacitive materials such as some metal oxides and electrically conductive polymers (ECPs) that have much higher theoretical capacitance than carbon-based materials. These materials have been reviewed in detail elsewhere [89,90]. Although many materials have been reported to exhibit pseudocapacitive behavior, they are very sensitive to the type and pH of the electrolytes and few of them are suitable for application in strong acid electrolytes. As previously mentioned in Section 1.3.2, RUO2 is one of the most extensively studied pseudocapacitive materials in H2SO4 electrolytes. 

Applications of conducting polymers include batteries (2), antistatic transparent films to protect sensitive microelectronic devices (2), antistatic fabrics (3), and sensors (4). Moreover, conducting polymers that change color when oxidized or reduced are the basis of smart windows (3). Blends of electrically conducting polymers have also been developed for applications such as rechargeable batteries (5), chemical and optical sensors (6), nonlinear optical devices (7), and light-emitting diodes (8). 

Chemical and Biochemical Sensors. The sensitivity of the electrical properties of conductive polymers to chemical stimuli suggests they may prove useful in a number of sensing applications. 

Synthetic polymers are best known for their insulating dielectric properties which have been exploited for numerous applications in both the electrical and electronic industries. It was found recently that some polymers can also be rendered conductive by an appropriate treatment, thus opening the way to a new field of applications of these materials (2, 3). Usually, electrical conductivity is obtained by doping a neutral polymer, rich in unsaturation, with donor or acceptor molecules. These polymers are rather difficult to synthesize, which makes them very expensive besides they are often sensitive to environmental agents, like oxygen or humidity, thus restricting their practical use to oxygen-free systems. 

Polymers have some specific properties due to their organic nature. Thermoplastics, as seen in Chapter 1, are independent organic macromolecules with some sensitivity to environmental parameters temperature, moisture, deleterious solids, liquids, gases and other chemical products. They are also sensitive to mechanical loading, especially cyclic loads. Their specific properties, such as electrical or optical properties, are also important for their applications. 

Polymers are organic materials and are sensitive to natural or artificial UV sources. This is of primary importance for outdoor exposure of unprotected parts and for some industrial applications such as electrical welding, photocopier light exposure devices. .. 

Because electronic and ionic conduction are so structure-sensitive, the simple rule-of-mixtures approach to estimating the conductivity and resistivity of composites is not normally of use. As a result, the conductivity of specific composites for specific applications must be experimentally determined. In the next two sections, we examine two examples of how composites can be used in electrical applications, and we describe the influence of each component on the electrical properties. The first example involves the electrical insulating properties of polymers, and the second one involves enhancing the electrically conducting properties of polymers. 

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