Electrochromic Composite Materials

Many conducting pol5miers such as polyaniline, polyazulene, polypyrrole, and pol3Ahiophene derivatives including PEDOT have been electros mthesized in various ILs [129, 130]. 

Inzelt, G. (1987J. Chemical and electrochemical syntheses of conducting polymers. In Conducting Polymers a New Era in Eiectrochemistiy, 2nd ed.. Chapter 4 (Springer Science Business Media] pp. 149-171. 

Bernier R, Bidan G., and Lefrant, S. [1999 ). Advances in SyntheticMetais Twenty Years of Progress in Science and Technology (Elsevier Science Tfechnology, Amsterdam, The Netherlands]. 

Roncali, J. [1992], Conjugated poly[thiophenes) Synthesis, functionalization, and appiications, Chem. Rev., 92, pp. 711-738. Gadgii, B., Damlin, R, Aaritaio, T, Kankare, ]., and Kvarnstrdm, C. (2013). Electrosynthesis and characterization of viologen cross linked thiophene copolymer, Electrochim. Acta, 97, pp. 378-385. Nalwa, H. S. (2001). Advanced Functional Molecules and Polymers Electronic and Photonic Properties, 3 (Gordon and Breach Science Publishers, Amsterdam, The Netherlands]. 

Walden, P. (1914]. Uber die MolekuiargrdiSe und elektrische Leitfahigkeit einiger geschmolzener Salze, Bull. Acad. Imper. Sci. St Petersburg, 8, pp. 405-422. 

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Nanocarbon hybrids have recently been introduced as a new class of multifunctional composite materials [18]. In these hybrids, the nanocarbon is coated by a polymer or by the inorganic material in the form of a thin amorphous, polycrystalline or single-crystalline film. The close proximity and similar size domain/volume fraction of the two phases within a nanocarbon hybrid introduce the interface as a powerful new parameter. Interfacial processes such as charge and energy transfer create synergistic effects that improve the properties of the individual components and even create new properties [19]. We recently developed a simple dry wrapping method to fabricate a special class of nanocarbon hybrid, W03 /carbon nanotube (CNT) coaxial cable structure (Fig. 17.2), in which W03 layers act as an electrochromic component while aligned... 

One of the big drawbacks associated with the use of many conducting polymers as electrochromic materials is their low cycle life stability. To overcome this, and other electrochromic properties, many composite materials have been studied. These composites include mixtures with other optically complementary, conducting polymers and inorganic electrochromes, such as tungsten trioxide and Prussian Blue, and colour enhancing agents or redox indicators, exemplified by the inherently electrochromic indigo carmine (1.96). °... 

For graphene/CP composite films, the goal of combining the materials has been both to obtain a mechanically more robust material and to combine the attractive properties of the individual components to obtain a superior material. As discussed above, graphene/CP composite materials can be S3mthesized by a range of different methods. In this section, electropolymerization of graphene/CP composite electrode materials and the direct use of such electrodes in the field of supercapacitors and electrochromic devices will be briefly summarized. 

Composite films of PB and poly(3-methylthiophene) capitalize on the transparent state of the reduced PB and the similar colored states of both PB and poly(3-methylthiophene) in their respective oxidized states. This composite switches from deep red, a contribution of poly(3-methylthiophene) in the neutral state, to dark blue in the oxidized state [241]. In addition to the additive electrochromic properties displayed by the materials in the composites, the improved adhesion of PB to the polymer films in comparison with electrode surfaces, along with efficient control of the amount of the composite materials deposited, are the advantages seen with this method. 

Leventis, N. and Y.C. Chung. 1990. Polyaniline—Prussian Blue novel composite material for electrochromic applications. J Electrochem Soc 137 3321—3322. 

PP can be provided with various electronic properties by doping it with various anions. The PP film incorporating iron bathophenanthroline disulfonic acid showed electrochromism due to the redox reaction of the complex When pyrrole was electropolyraerized in the presence of polymeric anions, the latter was incorporated in the formed PP film to give a new composite material Potassium polyvinylsulfate... 

Several other organic systems have been stndied as potential electrochromes because of their redox behaviour. These include carbazoles, methoxybiphenyls, fluorenones, benzoquinones, naphthaquinones and anthraqninones, tetracyanoquinodimethane, tetrathiafnlvalene and pyrazolines. ° Of particnlar interest are the 1,4-phenylenedi-amines, which form highly colonred species on oxidation. These, known as Wurster s salts, exemplified by Wnrster s Bine (1.97), are anodically colouring and this type of material has found nse in composite electrochromic systems for car rearview mirrors (see 1.5.4.1). 

Gaupp, C.L., Welsh, D.M., Ranh, R.D., and Reynolds, J.R. 2002. Composite coloration efficiency measurements of electrochromic polymers based on 3,4-alkylenedioxythio-phenes. Chemistry of Materials 14, 3964—3970. 

Electrochromic applications of the PAn and substituted PAn films [307a-h], composite films of PAn or its derivatives with other electrochromic materials [307i-m], silanized PAn films [306o] and photo-induced electrochromic reactions on semiconductor particles [307p]. Again, most other polymers can be used for this purpose as long as their oxidized and reduced states are stable and have different colors from that of neutral polymers. 

Owing to the intense research into PANI, one can ensure that new materials will be created in the coming months and years composites, co-polymers, (graft copolymers of PANI and nitrilic rubber [104]), PANI self-doped with organic acids, and so on. It was announced very recently that PANI electropolymerized in cam-phor.sulfonic acid (CSA) presented electrochromic properties analogous to PANI electropolymerized in common acids [105], In fact, it seems that PANl-CSA presents noteworthy stability during electrochromic cyclings [58]. 

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