SELENOPHENE DERIVATIVES FOR ELECTROCHROMIC APPLICATIONS Aydemir, Kadir M.S., Department of Chemistry Supervisor: Prof. Dr. Levent Toppare February 2008, 60 pages A novel selenophene-based monomer / 1,4-di(selenophen-2-yl) benzene (DSB), synthesized via Stille coupling reaction of 1,4 dibromobenzene and tributyl (2-selenophenyl) stannane and corresponding conducting homopolymer (Poly (DSB)) was electrochemically synthesized in the presence of tetrabutylammoniumhexafluorophosphate (TBAPF6) as the supporting electrolyte in dichloromethane. The resulting conducting polymer was characterized by Cyclic Voltammetry (CV), Fourier Transform Infra Red Spectrometry (FTIR) and Ultraviolet&ndash / Visible Spectrometry (UV-Vis Spectrometry). Spectroelectrochemistry analysis and kinetic studies of Poly (DSB) revealed &ndash / * transition (max) at 340 nm with almost zero percent transmittance (T%) concurrently with striking and rapid (0.6 s) absorbance change at near infrared region (1250 nm) with 35% percent transmittance, indicating that Poly (DSB) is a very suitable near infrared electrochromic material. Copolymer of selenophene with ethylenedioxythiophene (EDOT) was potentiostatically synthesized. Poly (selenophene-co-EDOT) was characterized by Cyclic Voltammetry, FTIR and UV-Vis Spectrometry. During spectroelectrochemistry studies, &ndash / * transition (max) was observed at 555 nm with a switching time of 1.4 s and 39% transmittance. Polaron and bipolaron bands were observed at 851 nm and 1299 nm, respectively. Switching time at 1299 nm was 1.8 s with a percent transmittance of 72. Copolymer of DSB with EDOT (Poly (DSB-co-EDOT)) was synthesized and characterized. max, polaron and bipolaron bands were observed at 457 nm, 696 nm and 1251 nm, respectively. A rapid switching time (0.2 s) with 12% transmittance was observed at 696 nm. At the near infrared region (1251 nm), satisfactory percent transmittance (35%) and a moderate switching time (1.75 s) were observed.

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Une surface est dite superhydrophobe si l’angle de contact d’une goutte d’eau avec cette surface est supérieur à 150°. Les domaines d’application de telles surfaces anti-adhérentes sont variées : du bâtiment avec l’élaboration de vitres anti-salissures au biomédical pour empêcher ou limiter l’adhésion bactérienne en passant par l’aéronautique. La superhydrophobie provient de la combinaison de deux paramètres : la structuration de la surface et la faible énergie de surface du matériau. Dans la plupart des références de la littérature, l’élaboration de telles surfaces s’effectue en plusieurs étapes. La polymérisation électrochimique de monomères conducteurs est une technique simple, rapide et reproductible pour obtenir des surfaces superhydrophobes. En effet, en une seule étape, le film de polymère se dépose et se structure. Cette méthode permet de contrôler les propriétés de mouillage en jouant sur les paramètres électrochimiques (charge de dépôt, substrat, sel électrolyte) ou sur la structure chimique du monomère. Ce travail porte sur l’élaboration et la caractérisation de films de polymères conducteurs obtenus par électrodéposition de dérivés du 3,4-éthylènedioxythiophene (EDOT), du 3,4-ethylènethiathiophene (EOTT) et du 3,4-propylenedioxythiophene (ProDOT) portant une chaîne hydrocarbonée de longueur variable. Des surfaces aux propriétés de mouillage polyvalentes (hydrophiles à superhydrophobes) ont été obtenues. De plus, l’influence de la part chimie et de la part physique sur l’angle de contact à l’eau a été déterminée pour les EDOT hydrocarbonés. Ce travail contribue à trouver une alternative aux composés fluorés. dans la domaine de la superhydrophobie. / Controlling wettability of a solid surface is important in many practical applications. This property, resulting from the combination a low surface energy material with a surface structuration, is commonly expressed by the contact angle of a water droplet on the surface. Surfaces with a water contact angle (θwater) larger than 150° are usually called superhydrophobic surfaces. Such surfaces are very interesting because of their expected self-cleaning or anti-contamination properties, which could be applied in various applications such as in biomedical devices, paint or in aeronautics for example. Among all the techniques to prepare superhydrophobic surfaces, electrochemical polymerization is a fast and versatile technique. In current literature on this field, the general approach is the use of highly fluorinated tails to reach the water-repellency. However, as observed in nature, fluorine is not necessary and can present environmental impacts. In this work, we focused on the synthesis of original monomers with hydrocarbon chain as hydrophobic part in order to find alternative to fluorine chemistry to prepare electropolymerized superhydrophobic surfaces. We succeeded to reach high water repellency (θwater > 150°) with hydrocarbon conducting polymers and we determined the influence of chemical and physical parts onto the water contact angle. We also found similar dewetting properties than the fluorinated series meaning the hydrocarbon conducting polymers could be a real alternative to fluorine chemistry.

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, &ldquo / electrochromism&rdquo / . 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.

Thiophene ended poly(ethylene oxide) (ThPEO) and random copolymer (RPEO) of 3-methylthienyl methacrylate and p-vinylbenzyloxy poly (ethyleneoxide) units were synthesized chemically. Further graft copolymerization of RPEO and ThPEO with pyrrole (Py) and thiophene (Th) were achieved in H2O - sodium dodecylsulfate (SDS), H2O - p-toluenesulphonic acid (PTSA) and acetonitrile (AN) - tetrabutylammonium tetrafluoroborate (TBAFB) solvent electrolyte couples via constant potential electrolyses. Characterizations were performed by cyclic voltammetry (CV), nuclear magnetic resonance spectroscopy (NMR), and fourier transform infrared spectroscopy (FTIR). The morphologies of the films were examined by scanning electron microscopy (SEM). Conductivities of the samples were measured by using four-probe technique. Moreover, spectroelectrochemical and electrochromic properties of the copolymers obtained from thiophene were investigated by UV-Vis spectrometry and colorimetry. . Immobilizations of alcohol oxidase and polyphenol oxidase enzymes were performed in the matrices obtained via copolymerization of ThPEO and RPEO with pyrrole. Immobilization was carried out via entrapment of enzyme in matrices during the polymerization of pyrrole. Temperature optimization, operational stability and shelf-life of the enzyme electrodes were investigated. Maximum reaction rate (Vmax) and Michaelis-Menten constant (Km) were determined. It is known that wine includes phenolic groups that give astringency in high concentrations. Polyphenol oxidase (PPO) converts mono and diphenols to quinone. By analyzing the product, one can find out the amount of phenolic groups. By using the enzyme electrodes via immobilization of PPO, amount of phenolics in different wines were analyzed.

2,3-Dihydro-5-(10-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)anthracen-9-yl)thieno [3,4-b][1,4]dioxine (DTAT) was synthesized via linking 3,4-ethylenedioxy thiophene (EDOT) on anthracene by Stille coupling. Homopolymer P(DTAT) was achieved by electrochemical techniques. The polymer, P(DTAT) was electrosynthesized by anodic oxidation of the corresponding monomer in the presence of 0.1 M LiClO4 as the supporting electrolyte in acetonitrile (ACN) solution. Copolymer of DTAT in the presence of EDOT was synthesized via potentiodynamic method in ACN/LiClO4 (0.1 M) solvent-electrolyte couple. Structural characterizations of the sample was carried out via 1H-Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). Electrochemical behaviors of the monomer and polymers were determined by Cyclic Voltammetry (CV). Electrochromic and spectroelectrochemical behavior of the polymers were investigated on ITO glass electrode, and their ability of employment in device construction was examined. Spectroelectrochemistry analysis of P(DTAT) revealed an electronic transition at 505 nm corresponding to &amp / #960 / -&amp / #960 / * transition with a band gap of 1.57 eV. In order to investigate electronic structure of the copolymers obtained by different applied potentials, spectroelectrochemistry studies were performed. Electrochromic investigations showed that P(DTAT) switches between yellow and blue while P(DTAT-co-EDOT) was found to be multichromic, switching between claret red neutral state, a gray and a red intermediate state, and a blue oxidized state. 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(DTAT-co-EDOT) with poly(3,4-ethylenedioxythiophene) (PEDOT) were constructed. Spectroelectrochemistry and electrochromic switching of the device was studied. They were found to have good switching times and reasonable contrasts.

A novel electrically conducting polymer, poly(2-dodecyl-4,7-di(selenophen-2-yl)benzotriazole) (Poly(SBT)), containing selenophene as a strong donor and benzotriazole as a strong acceptor group was synthesized by electrochemical polymerization. Homopolymerization and copolymerization ( in the presence of 3,4-ethylenedioxythiophene (EDOT) ) was achieved in acetonitrile/ dichloromethane(95/5 v/v) with 0.1M tetrabutylammonium hexafluorophosphate (TBAPF6). The electrochemical and optical properties of homopolymer and copolymer were investigated by Cyclic voltammetry, UV-Vis, near IR Spectroscopy. Cyclic voltammetry and spectroelectrochemistry studies demonstrated that homopolymer can be reversibly reduced and oxidized (both n- and p-doped) between -1.9 V and 1.4 V, at a scan rate of 100 mV/s. Optical contrast was calculated as 32% and 56% with a switching time of 2.4 s and 0.4 s at 511 and 1200 nm respectively. Poly(SBT) exhibits a &amp / #955 / max value of 511nm and a band gap of 1.67eV.

In the first part of this dissertation, poly(methylsilyne) was produced both in small and large-scales. In the small-scale, the aim was to synthesize the polymer by electrochemical polymerization of methyltrichlorosilane at a constant potential of -6 V supplied by batteries, using sodium dodecyl sulfate (SDS) as the supporting electrolyte. The polymer was characterized by 1H-NMR, FTIR, UV-Visible Spectroscopy and GPC in addition to its distinctive yellow color. The yellow color and the 1H-NMR, FTIR, UV-Visible and GPC results proved that poly(methylsilyne) was produced successfully in small-scale. In the second part of the synthesis, the objective was to scale-up the electrochemical synthesis of poly(methylsilyne) while investigating the effects of the parameters like the electrode, solvent and supporting electrolyte types, monomer/solvent ratio and reaction time on the synthesis. Although successful results were obtained in large-scale synthesis with acetonitrile and SDS, the problems with the reproducibility of the synthesis were solved using a system containing 1.2-dimethoxyethane (DME) and tetrabutylammonium perchlorate (TBAP). In the second part of the dissertation, the aim was to prepare polypropylene/silicon-based preceramic polymer blends and to characterize them in terms of flammability, thermal and mechanical properties and morphologies. In order to investigate the effect of the silicon-based preceramic polymers, two different polymers were used: poly(methylsilyne) (PMSy) and allylhydridopolycarbosilane (SMP-10) where the latter was a commercially available silicon carbide precursor. Triphenylphosphate (TPP) and a metal complex were also used in polypropylene based composites to gain a synergy with the silicon containing polymers. The polymer composites were prepared using a twin-screw extruder and molded in an injection molding machine. As a result of the flammability tests, it was seen that in order to achieve a significant decrease in the flammability of polypropylene, at least 20 wt% additive was needed. Furthermore, it was observed that the most significant improvement in flame retardancy was obtained in PP/10SMP/5TPP/5M sample containing 10 wt% SMP-10, 5 wt% TPP and 5 wt% metal complex with a limiting oxygen index (LOI) value of 23.5%. This was explained by the synergy obtained by SMP-10, TPP and the metal complex. With the addition of these silicon containing polymers, thermal properties of the composites increased to a great extent. For the mechanical properties, it was seen that impact strength of the composites significantly increased with the addition of SMP-10, PMSy and TPP.

A monomer, 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl) benzenamine (SNS-NH2), was synthesized via the reaction of 1,4-di(2-thienyl)-1,4-butanedione with benzene-1,4-diamine. Chemical polymerization of the monomer yielded a polymer which was completely soluble in organic solvents. The chemical structures of both the monomer and the polymer were characterized by Nuclear Magnetic Resonance Spectroscopy (1H-NMR and 13C-NMR) and Fourier Transform Infrared (FTIR) Spectroscopy. The average molecular weight of the chemically synthesized polymer was determined by Gel Permeation Chromatography (GPC) as Mn = 2.2x103 g/mol. The electrochemical oxidative polymerization of SNS-NH2 was carried out via potentiodynamic electrolysis in the presence of LiClO4, NaClO4 (1:1) supporting electrolyte in acetonitrile. Electrochemical copolymerization of SNS-NH2 in the presence of 3,4-ethylenedioxythiophene (EDOT) was achieved in acetonitrile (ACN) / NaClO4/LiClO4 (0.1M) solvent-electrolyte couple via potentiodynamic electrolysis. Conductivities of samples were measured by four probe technique. Cyclic Voltammetry (CV) and Ultraviolet&ndash / Visible Spectroscopy were used to investigate electrochemical behavior of the monomer and redox reactions of conducting polymers. Surface morphologies of the polymer films were investigated by Scanning Electron Microscope (SEM). Second part of the study was devoted to investigate the one of most interesting property of conducting polymers, the ability to switch reversibly between the two states of different optical properties, &lsquo / electrochromism&rsquo / . The electrochromic properties of the conducting polymers were investigated via spectroelectrochemistry, kinetic and colorimetry studies. Spectroelectrochemistry analysis of homopolymer, P(SNS-NH2), reflected electronic transitions at 376 and 650 nm indicating &amp / #960 / -&amp / #960 / * transition and polaron band formation respectively. The polymer has an electronic bandgap of 2.12 eV with a yellow color in the fully reduced form and a blue color in the fully oxidized form. Switching ability of the homopolymer was evaluated by kinetic studies upon measuring the % transmittance as 20.7 % at the maximum contrast point. The spectroelectrochemical behavior of the P(SNS-NH2-co-EDOT) compare to that of the homopolymer revealed solid evidence of copolymerization based upon the differences in the spectral signatures. Copolymer revealed multichromic property with five different colors at different applied potentials. Colorimetry studies for P(SNS-NH2-co-EDOT) proved that it is possible to provide fine tuning of these colors by varying applied potential during synthesis. The results of colorimetry, spectroelectrochemistry and FTIR studies showed the possible control of the color of the electrochromic material in a predictable, controlled and reproducible manner. As the last part of the study, dual-type complementary colored electrochromic devices (ECD) using P(SNS-NH2) and P(SNS-NH2-co-EDOT)/poly(3,4-ethylenedioxythiophene) (PEDOT) in sandwich configuration were constructed and evaluated. Spectroelectrochemistry, electrochromic switching and open circuit stability of the devices were investigated by UV-Vis Spectrophotometer and Cyclic Voltammetry. They have shown to possess good switching times, reasonable contrasts and high stabilities.