Polypyrroles, properties optical

Few reports on polypyrrole-based electrochromic devices have appeared due to air instability of the neutral undoped state of the polymer. A polypyrrole-based optical window performing in water has been proposed [423]. DePaoli et al. [424] have produced a device from electrochemically deposited polypyrrole dodecylsulfonate which results in improved properties over polypyrrole doped with perchlorate. 

The second method is the synthesis of copolymers or derivatives of a parent conjugated polymer with more desirable properties. This method is the more traditional one for making improvements to a polymer. It modifies the structure of the polymer to increase its processibility without compromising its conductivity or its optical properties. All attempts to do this on polyacetylene have failed as they always significantly reduced its conductivity. However, such attempts on polythiophenes and polypyrroles proved more fruitful. 

Intercalation of electroactive polymers such as polyaniline and polypyrrole in mica-type layered silicates leads to metal-insulator nanocomposites. The conductivity of these nanocomposites in the form of films is highly anisotropic, with the in-plane conductivity 10 to 10 times higher than the conductivity in the direction perpendicular to the film. Conductive polymer/oxide bronze nanocomposites have been prepared by intercalating polythiophene in V2O5 layered phase, which is analogous to clays. °° Studies of these composites are expected not only to provide a fundamental understanding of the conduction mechanism in the polymers, but also to lead to diverse electrical and optical properties. 

As with polypyrrole (PPy), the electrical, chemical, and mechanical properties of polyaniline (PAn) are inextricably linked. In addition, PAn has spectacular optical and chromic properties that distinguish it from other conducting electroactive polymers (CEPs). The current state of knowledge concerning properties of PAn is reviewed in this chapter. 

S. Kawabata, H. Yoneyama and H. Tamura, Redox behavior and electrochromic properties of polypyrrole films in aqueous solutions, Bull. Chem. Soc. Jpn., 1984, 57, 2247 P.C. Bookbinder and M.S. Wrighton, Electrochromic polymers covalently anchored to electrode surfaces. Optical and electrochemical properties of a viologen-based polymer./ Electrochem. Soc., 1983,130, 1080. 

The first studies by UV-visible transmission spectroscopy were carried out using an optically transparent electrode (OTE) such as indium oxide [140,141]. Unfortunately an OTE does not allow the nature and the structure of the electrode material to be changed and these play a key role in electrocatalytic processes. Only reflectance spectroscopy is able to investigate in situ, various electrode materials [142], This was effectively checked for the first time with cobalt porphyrin-doped polypyrrole films using the electroreflectance technique [106,143]. This allowed the characterization of the redox properties of the modified PPy electrode and the determination of the redox potential of the Co"VCo" couple. The catalytic effect towards the ORR was also... 

A. Watanabe, M. Tanaka, and J. Tanak, Electrical and optical properties of a stable synthetic metallic polymer polypyrrole. Bull. Chem. Soc. Jpn., 54, 2278-2281 (1981). 

K. Dutta and S.K. De, Transport and optical properties of Si02-polypyrrole nanocomposites... 

J. Jang, Y. Nam, and H. Yoon. Fabrication of polypyrrole-poly(A-vin-ylcarbazole) core-shell nanoparticles with excellent electrical and optical properties. Ac v. Mater, 17(11) 1382-1386, June 2005. 

FIGURE 7.5. Evolution of the optical properties (a,b) and film thickness(c) as a function of time for a polypyrrole film grown potentiostatically on a Pt sputter-deposited film electrode at +0.60 V (SCE) using an aqueous solution of pyrrole (0.025 M) and KNO3 (0.5 M). (From Ref. 19). 

Variation in Polypyrrole Optical Properties As a Function of Growth Conditions... 

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