Date

2006

Author

Yiğitsoy, Başak

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2,5-Di(thiophen-2-yl)-1-p-tolyl-1H-pyrrole (DTTP) was synthesized via reaction of 1,4-di(2-thienyl)-1,4-butanedione with p-toluidine in the presence of catalytical amount of p-toluenesulfonic acid (PTSA). Homopolymer P(DTTP) was achieved both by chemical and electrochemical techniques. Chemical polymerization of the monomer yielded a soluble polymer. The average molecular weight was determined by gel permeation chromatography (GPC) as Mn: 2.5x103 g/mol. The monomer was electrochemically polymerized in the presence of LiClO4, NaClO4 (1:1) as the supporting electrolyte in acetonitrile. Copolymer of DTTP in the presence of EDOT was synthesized via potentiodynamic method in ACN/ NaClO4/LiClO4 (0.1 M) solvent-electrolyte couple. Structural characterizations of samples were carried out via 1H, 13C Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). Electrochemical behaviors of monomer and polymers were determined by Cyclic Voltammetry (CV). The morphologies of the polymer films were examined by Scanning Electron Microscopy (SEM). Conductivities of the films were measured by four probe technique. Electrochromic and spectroelectrochemical behavior of the polymers coated on ITO glass electrode were investigated, and their ability of employment in device construction was examined. Spectroelectrochemistry analysis of P(DTTP) revealed an electronic transition at 428 nm corresponding to п п* transition with a band gap of 2.1 eV whereas P(DTTP-co-EDOT) revealed an electronic transition at 448 nm corresponding to п- п* transition with a band gap of 1.8 eV. Electrochromic investigations showed that P(DTTP) switches between greenish yellow and blue while P(DTTP-co-EDOT) was found to be multichromic, switching between red, yellow and blue. Switching time of the polymers was evaluated by a kinetic study upon measuring the percent transmittance (%T) at the maximum contrast point. Dual type polymer electrochromic devices (ECDs) based on P(DTTP) and P(DTTP-co-EDOT) with poly(3,4-ethylenedioxythiophene) (PEDOT) were constructed. Spectroelectrochemistry, electrochromic switching and open circuit stability of the devices were studied. They were found to have good switching times, reasonable contrasts and optical memories.

Subject Keywords

Polymers., Macromolecules.

URI

http://etd.lib.metu.edu.tr/upload/12607305/index.pdf
https://hdl.handle.net/11511/16253

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Graduate School of Natural and Applied Sciences, Thesis