The electrochromic properties of conducting polymers

O'Malley, Hubert A. (2007) The electrochromic properties of conducting polymers. (PhD thesis), Kingston University, .


Over the past number of years, polymers with delocalised [pi]-orbitals have been of interest due to their electrical conducting properties. Exposing these polymers to electron donating or accepting dopants, remarkably alters the nature of these materials. In this project it was planned to synthesise and investigate the physical and chemical and electrochemical properties the "polyquinoxaline" family of materials. In order to investigate these materials, synthesis of 5,14-dihydro-5,7,12,14-tetraazapentacene(L5H[sub]2),7,16-dihydro-5,7,9,14,16,18-hexaazaheptacene (L7H[sub]2),7,20-dihydro-5,7,9,11,16,18,20,22-octaazanonacene (L9H[sub]2) and "Polyquinoxaline" (poly[1,6-dihydropyrazino(2,3 -g)-quinoxaline-2,3,8-triyl-7(2H)-ylidene-7,8-dimethylidene was carried out. A number of techniques such as FTIR, solid state NMR, Ultraviolet-Visible spectroscopy have been used in characterising these compounds. Thermogravimetric Analysis and annealing studies of the oligomers were carried out in order to establish optimum crystals growth conditions to aid crystallographic studies. The oligomers (L5H[sub]2) and (L7H[sub]2) were vacuum evaporated on ITO glass substrate. Studies using cyclic voltammetry (CV), and in-situ spectroelectrochemical techniques were used to measure the electrochromic changes and diffusion kinetics in the oligomers upon doping. A comparison with phenazine (L3) has been made where possible in order to complete the available series.

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