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Synthesis of polythiophene and polypyrrole derivatives and their application in electrochromic devices

Ak, Metin
Different substituted thiophene and pyrrole monomers namely hexamethylene (bis-3-thiopheneacetamide) (HMTA), N-(4-(3-thienylmethylene)-oxycarbonylphenyl)maleimide (MBThi), 2,4,6-Tris-(4-pyrrol-1-yl-phenoxy)-[1,3,5]triazine (TriaPy), 2,4,6-Tris-(thiophen-3-ylmethoxy)-[1,3,5] triazine (TriaTh), and N-(2-(thiophen-3-yl)methylcarbonyloxyethyl) maleimide (NMT) were synthesized. The chemical structures of the monomers were characterized by Nuclear Magnetic Resonance (1H-NMR and 13C-NMR) and Fourier Transform Infrared (FTIR) Spectroscopies. Electrochemical behavior of the monomers in the presence and absence of comonomers were studied by cyclic voltammetry. Subsequently, monomers were homopolymerized and copolymerized via electrochemical methods and the resultant polymers were characterized by FTIR, Scanning Electron Microscopy (SEM) and conductivity measurements. Second part of the study was devoted to investigate one of most interesting property of conducting polymers, the ability to switch reversibly between the two states of different optical properties, “electrochromism”. In recent years there has been a growing interest in application of conducting polymers in electrochromic devices. Thus, electrochromic properties of the synthesized conducting polymers were investigated by several methods like spectroelectrochemistry, kinetic and colorimetry studies. Spectroelectrochemistry experiments were performed in order to investigate key properties of conjugated polymers such as band gap, maximum absorption wavelength, the intergap states that appear upon doping and evolution of polaron and bipolaron bands. Switching time and optical contrast of the homopolymers and copolymers were evaluated via kinetic studies. Results implied the possible use of these materials in electrochromic devices due to their good electrochromic properties.