ABSTRACT Covalent Immobilization of Glucose Isomerase on Poly (2-hydroxyethyl methacrylate) Particles Yildiz, Hakan &Uuml / mit M.S., Department of Chemistry Supervisor: Prof. Dr. Nesrin Hasirci July 2004, 54 pages In this study, poly (2-hydroxyethyl methacrylate), P(HEMA), particles were prepared by suspension polymerization of the monomer 2-hydroxyethyl methacrylate with addition of ethylene glycol dimethyacrylate, EGDMA, as cross linker. Glucose isomerase, GI, enzyme was covalently immobilized on the prepared P(HEMA) particles after activation of the particles with cyanuric chloride. The activities of the free and immobilized enzymes were measured with Ethanol-Carbazole method. The immobilization of GI on P(HEMA) particles promoted enzyme stability and as a result, the enzyme became more stable to temperature, storage, and reuse. For maximum substrate conversion, optimum temperature was determined as 70 oC for free GI and this value shifted to 60 oC for immobilized enzyme. Optimum pH for maximum substrate conversion was found to be 7.0 for free GI and 8.0 for immobilized GI. The change of enzyme activity with substrate concentration were determined to calculate Km and Vmax values of the free and immobilized enzymes. Km values were found to be 1.7x10-2 mol/L and 3.1x10-1 mol/L while Vmax values were 1.01x10-4 mol/L.min, 1.65x10-3 mol/L.min for free and immobilized GI, respectively. Reuse capability of immobilized GI on P(HEMA) particles was measured and compared with commercial GI. Both systems retained 80 % of their original activities after 40th use, within 6 days. The change of enzyme activities upon storage were detected at certain time intervals for the samples stored in buffer solution at 4 oC. Immobilized enzyme was retained 60% of its original activitiy in 60 days of storage at 4 oC. Immobilized GI and commercial GI both retained 90% of their activities under continuous flow after 180 mL of substrate solution passed through the column.

ABSTRACT SYNTHESIS AND CHARACTERIZATION OF POLY(DIHALOPHENYLENE OXIDE)S AND ITS DERIVATIVES FROM DIAMMINE BIS(TRIHALOPHENOLATO) Cu(II) COMPLEXES Sonsuz, Muammer M.S., Department of Chemistry Supervisor: Assoc. Prof. Dr. G&uuml / ls&uuml / n G&ouml / kaga&ccedil / Co-Supervisor: Prof. Dr. Duygu Kisak&uuml / rek September 2004, 62 pages In this study, synthesis and characterization of poly(dihalophenylene oxide)s were done by thermal decomposition of diamminebis(trichlorophenolato) copper(II) and diamminebis(tribromophenolato) Cu(II) complexes in solid state. 2,4,6-trichlorophenol (TCP), 2,4,6-tribromophenol (TBP) and ammonia were used as ligands in the complex syntheses. The complexes were characterized by means of X-ray diffraction, FTIR, DSC, mass spectroscopy, magnetic susceptibility and C, H, N elemental analyses. Synthesized complexes were decomposed thermally in solid state for the production of poly(dihalophenylene oxide)s. Polymerizations were carried out at two different conditions. In the first condition, the decomposition time was kept constant at 3 hours and temperature was varied for each sample to observe the effect of temperature on decomposition. In the second condition, the decomposition temperature was kept constant at maximum conversion temperature and the period of time was varied from 3 hours to 48 hours in order to define the effect of time on the decomposition. Synthesized polymers were characterized by FTIR, 1H-NMR, 13C-NMR, DSC, SEM, FAAS and viscometric measurements. At the end of the study, it was observed that, the percent conversion and the structure of the polymeric product depend on polymerization condition and the type of the starting complex.

Acetylenedicarboxylic acid monopotassium salt, ADCA-K, was polymerized by radiation induced solid-state and chemical initiator induced solution polymerization methods. Radiation induced solid-state polymerization was carried out by Co-60 g-radiation at room temperature. The powder polymer obtained was soluble in water but insoluble in common organic solvents. The solution polymerization initiated by benzoylperoxide was carried out in an oil bath at 90&deg / C. The polymer obtained was soluble in water but insoluble in dimethylsulfoxide. In the first stage of the polymerization, H2O, CO and/or CO2 gases were evolved and the polymerization was proceeded on the acetylene group. The polymers obtained were characterized by FT-IR, DSC, TGA-FTIR, NMR and DP-MS methods. The crystal structure effect on polymerization was investigated by X-Ray method. The monomer is monoclinic with a space group of C2/c. The unit cell parameters are a=795.4, b=1192.6, c=591.8 pm and b=105.40. Polymer showed a partial polycrystalline structure. The larger fraction of polymer has identical crystal structure to that of the monomer. Therefore, polymerization takes place a topotactic mechanism.

P-xylene-bis(diethylsulphonium chloride) (PXBDC) monomer was synthesized by the reaction of &amp / #945 / ,&amp / #945 / -dichloro-p-xylene with tetrahydrothiophene or diethyl sulphide. Electrochemical behavior of this monomer (PXBDC) was examined by cyclic voltametry. Polymerization was achieved both by using electrochemical and chemical polymerization techniques. In the electrochemical technique, PPV was synthesized by constant potential electrolysis in acetonitrile-tetrabutylammonium tetrafluoroborate (TBAFB) solvent-electrolyte couple. The polymer obtained from the electrode surface was converted to the poly(p-phenylene vinylene) (PPV) by the thermal elimination reaction of diethyl sulphide and HCl. Also, PPV was doped via electrochemical doping with ClO4- dopant ion. The chemical structures were confirmed both by Nuclear Magnetic Resonance Spectroscopy (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The thermal behavior of chemically and electrochemically synthesized conducting polymers were investigated by Differential Scanning Calorimetry (DSC). Also, electrochromic and spectroelectrochemical properties of PPV was investigated by using UV-VIS spectrophotometer.

ABSTRACT IMMOBILIZATION OF INVERTASE, POLYPHENOL OXIDASE AND GLUCOSE OXIDASE IN CONDUCTING COPOLYMERS OF THIOPHENE-CAPPED POLYTETRAHYDROFURAN AND PYRROLE B&ouml / y&uuml / kbayram, AySe Elif Ph.D., Department of Chemistry Supervisor: Prof. Dr. Levent Toppare January 2005, 123 pages Immobilization of invertase, polyphenol oxidase (PPO) and glucose oxidase (GOD) enzymes were performed in electrochemically synthesized two types of conducting copolymers. One end and two end thiophene-capped polytetrahydrofuran (TPTHF-1 and TPTHF-2) were copolymerized with pyrrole under conditions of constant potential electrolysis. The copolymers were characterized by thermal, spectroscopic and scanning electron microscopy analyses. Immobilization was carried out via entrapment of enzymes in two types of matrices during the copolymerization of pyrrole with the insulating polymers in the presence of sodium dodecyl sulphate (SDS). Kinetic parameters: Maximum reaction rate (Vmax) and Michaelis-Menten constant (Km) were determined for the enzyme electrodes. Temperature optimization, pH optimization, operational stability and shelf-life of the enzyme electrodes were investigated. Enzyme electrodes of polyphenol oxidase and glucose oxidase were used to determine the amount of their substrates in samples. Polyphenol oxidase converts mono and diphenols to quinone. Amount of phenolic compounds in two kinds of wines were determined by analyzing the quinone amount. Glucose oxidase converts &amp / #61538 / -D-glucose to D-glucono-1,5-lactone. Glucose amount was determined in two kind of factory-produced orange juices by analyzing D-glucono-1,5-lactone.

Two new monomers / 2-benzyl-5,12-dihydro-2Hpyrrolo[ 3&rsquo / ,4&rsquo / :2,3][1,4]dioxocino[6,7-b]quinoxaline (DPOQ) and 5,12- dihydrothieno[3&rsquo / ,4&rsquo / :2,3][1,4]dithiocino[6,7-b]quinoxaline (DTTQ), were synthesized. The chemical structures of the monomers were characterized by Nuclear Magnetic Resonance (1H-NMR), Fourier Transform Infrared (FTIR) and Mass Spectrometry (MS). Copolymer of DPOQ with bithiophene (BT) was synthesized via potentiostatic electrochemical polymerization in acetonitrile (ACN)-tetrabutylammonium tetrafluoroborate (TBAFB) solvent-electrolyte couple. For DTTQ, copolymerization with bithiophene was achieved via potentiodynamic method in dichloromethane (DCM)-tetrabutylammonium hexafluorophosphate (TBAFP) solvent-electrolyte couple. Characterizations of the resulting copolymers were performed by cyclic voltammetry (CV), FTIR, Scanning Electron Microscopy (SEM) and UV-Vis Spectroscopy. Four-probe technique was used to measure the conductivities of the samples. Moreover, the spectroelectrochemical and electrochromic properties of the copolymer films were investigated. In addition, dual type polymer electrochromic devices (ECDs) based on P(DPOQ-co-BT) and P(DTTQ-co-BT) 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.

The synthesis of high molecular weight copolymer of carbon disulphide (CS2) and propylene oxide (PO) has not reported in literature. In the present work, zinc isopropyl xanthate (Zn(Xt)2) was used as catalyst for the copolymerisation of PO and CS2 into high copolymer. However, the product can be fractionated into high and low molecular weight components. High molecular weight copolymer was rubbery products, but low molecular weight copolymers were oily products containing cyclic dithiocarbonates. Copolymers were characterized by elemental, end group analysis, DSC, TGA, GPC, Light Scattering, UV, IR, NMR spectroscopy, polarized microscopy and refractometry. Copolymerization process was zeroth order with respect to monomers, and its non-terminated but suffered from several types of transfer reactions. As a result of transfer reactions S-(C=S)-S, O-(C=S)-O, O-(C=O)-O groups in the backbone of copolymer and SH groups at the chain terminals and cyclic dithiocarbonates are formed. Apart from SH groups, OH and double bonds were found and their amounts were determined at the chain terminals. Copolymers with high mole fractions of PO units (F1) in the copolymer are crystallized in the shape of Malta&amp / #8217 / s Cross. Melting points of products were obtained from DSC. The F1 values are calculated from elemental analysis as well as zeroth order rate constants and from melting point of the crystals. All three results were in close agreement and changed between 0.9 &amp / #8211 / 0.7. However, these ratios depend on reaction conditions (temperature, catalyst and monomer concentrations, time and dielectric constant of reaction medium). A mechanism for coordination-copolymerization on the basis of above observation was proposed.

ABSTRACT SYNTHESIS AND ELECTROCHROMIC PROPERTIES OF CONDUCTING POLYMERS OF SUCCINIC ACID BIS-(2-THIOPHEN-3-YL-ETHYL) ESTER AND THEIR USE IN ELECTROCHROMIC DEVICES Sa&ccedil / an, Lale M.Sc., Department of Chemistry Supervisor: Prof. Dr. Levent Toppare June 2006, 59 pages A new monomer / succinic acid bis-(2-thiophen-3-yl-ethyl)ester (SATE) was synthesized through the esterification reaction of 2-thiophen-3-yl-ethanol and succinyl chloride. The chemical structure of monomer was characterized via Nuclear Magnetic Resonance Spectroscopy (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). Electrochemical behaviors of SATE alone and SATE in the presence of thiophene were studied by cyclic voltammetry (CV). The synthesis of homopolymer and copolymer were achieved via constant potential electrolysis. Both homopolymer (PSATE) and copolymer [P(SATE-co-Th)] were characterized by various techniques including cyclic voltammetry, FTIR, Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Thermal Gravimetry Analysis (TGA) and UV-VIS Spectrophotometer. Conductivities of samples were measured by four probe technique. The electrochromic properties of the polymers were investigated via spectroelectrochemistry, colorimetry and switching studies. In addition, dual type electrochromic devices (ECDs) composed of PSATE, P(SATE-co-Th) and poly(3,4-ethylenedioxythiophene) (PEDOT) were constructed and evaluated. Spectroelectrochemistry, switching ability and stability of the devices were investigated by UV-Vis Spectrophotometer and Cyclic Voltammetry. They have shown to possess good switching times, reasonable contrasts, high stabilities and optical memories.

A new monomer / 1-(4-Nitrophenyl)-2,5-di-2-thienyl-1H-pyrrole SNSNO2 was synthesized through the Knorr-Paal condensation reaction of 1,4-di-2-thienyl-1,4-butanedione and p-nitroaniline. The chemical structure of monomer and polymer were characterized via Nuclear Magnetic Resonance Spectroscopy (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). Chemical polymerization produced a polymer which was completely soluble in organic solvents. Electrochemical behaviors of SNSNO2 and SNSNO2 in the presence of EDOT were studied by cyclic voltammetry (CV). The synthesis of homopolymer and copolymer were achieved via constant potential electrolysis. Both homopolymer P(SNSNO2) and copolymer P(SNSNO2-co-EDOT) were characterized by various techniques including cyclic voltammetry, FTIR, Scanning Electron Microscopy (SEM) and UV-VIS Spectrophotometer. Conductivities of samples were measured by four probe technique. The electrochromic properties of the polymers were investigated via spectroelectrochemistry, colorimetry and switching studies. In addition, dual type electrochromic devices (ECDs) composed of P(SNSNO2), P(SNSNO2-co-EDOT) and poly(3,4-ethylenedioxythiophene) (PEDOT) were constructed and evaluated. Spectroelectrochemistry, switching ability and 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.

Polyaniline was chemically synthesized at three different temperatures of 25, 0, and -25oC, by oxidative polymerization with ammonium peroxidisulfate at equimolar of aniline to oxidant ratio and 1M HCl. The resulted polyaniline was in a powder form which was characterized by several techniques such as: electrical conductivity, elemental analysis, thermal analysis, wide-angle X-Ray diffraction, and scanning electron microscope. The solution properties of the reduced polymer were studied by viscometry, static and dynamic light scattering. It was found that as the polymerization temperature decreased, the molecular weight, crystallinity, and thermal stability of polyaniline increased, while the electrical conductivity was independent of the polymerization temperature. Moreover, the morphology of the polymer was changed from granular to tubular with reducing polymerization temperature. Viscometry and static light scattering showed that polyaniline has a flexible random coil conformation when dissolved in N-methyl-2-pyrrolidinone which proved to be a good solvent for this polymer. Dynamic light scattering indicated that the polymer solution is a polyelectrolyte with high hydrodynamic radius at low polymer concentrations. All mechanical features except Young&#039 / s modulus of polyaniline-filled low density polyethylene composites became poorer as polyaniline content increased. Moreover, a sudden increase in the electrical conductivity with increasing polyaniline contents was also observed. The conductivity of the tubular composites of multi wall nanotubes (MWNTs)-filled polyaniline increased with increasing MWNTs loading, and became weakly temperature dependent. The morphological analysis indicated that the MWNTs were well dispersed and isolated, and the tubes became crowded proportionally to MWNTs weight percent used in the composites.