Duygu Kisakürek

Characterization of poly(dihalophenylene oxides) in solution

Several different dihalophenylene oxide polymers prepared by thermal decomposition of halophenoxo copper complexes were studied in toluene using light scattering. For polymers of molecular weight around 5 × 104, those obtained from 4-bromo-2,6-dichlorophenoxide, 2-chloro-4,6-dibromophenoxide and 2,4,6-tribromophenoxide appear to be relatively linear with higher values of 〈S2〉12, whereas those obtained from 2,4,6-trichlorophenoxide and 2-bromo-4,6-dichlorophenoxide appear to have branched or condensed structures with lower values of 〈S2〉12. Values for the intrinsic viscosities and second virial coefficients were measured from ∼17 to 50°C for poly(dichlorophenylene oxides) synthesized from 2,4,6-trichlorophenoxide (Mw = 5.3 × 104) and from 4-bromo-2,6-dichlorophenoxide (Mw = 2.49 × 105). These quantities both pass through a maximum as the temperature increases.

Synthesis and characterization of poly(dihalophenylene oxides) by thermal decomposition of copper complexes with tetramethylethylenediamine and ethylenediamine ligands

Abstract Thermal polymerization of bis(trihalophenoxo)- N,N,N′,N′ -tetramethylethylenediamine copper( ii ) and bis(trihalophenoxo)ethylenediamine copper( ii ) was achieved in toluene at 70°C. The dependences of intrinsic viscosity and the percentage yield of the polymers on a sequence of increasing decomposition times of copper complexes were investigated. Structural analyses of the polymers were carried out using mainly 1 H nuclear magnetic resonance spectroscopy and differential scanning calorimetry. 1,4-Catenation was highly favoured over 1,2-addition in 4-bromo-2,6-dichlorophenoxide- and 2,4,6-triiodophenoxide- (with ethylenediamine ligand) and 2,4,6-triiodophenoxide- (with tetramethylethylenediamine ligand) derived polymers. However, polymers synthesized from 2,4,6-trichlorophenoxide with either ligand displayed a selectivity in favour of 1,2-catenation, whereas for 2,4,6-tribromophenoxide with ethylene diamine ligand, 1,4-catenation and ortho substitution took place at roughly equal rates.

Synthesis and characterization of poly(dichlorophenylene oxide)s through solid state thermal decomposition of bis(pyridine)bis(trichlorophenoxo)copper(II) complexes

Abstract Thermal polymerization of bis(pyridine)bis(trichlorophenoxo)copper(II) was achieved in the solid state for the first time. The time and temperature effect on polymer molecular weight, percentage yield and the structure of polymer was first studied, at constant temperature and then for constant decomposition time. Polymers were characterized by i.r., 1 H n.m.r. and 13 C n.m.r. The molecular weights of the polymers were obtained by viscometric measurements at 30°C in toluene and glass transition temperatures were obtained by d.s.c.

Synthesis of poly(dihalophenylene oxide)s by solid state thermal decomposition of bis(4-chloro-2,6-dibromo phenoxo) ethylenediamine copper (II) complex

Abstract In this study the synthesis of poly(dihalophenylene oxides) by the solid state thermal decomposition of a bis (4-chloro-2,6-dibromo phenoxo) ethylenediamine copper (II) complex was achieved. Yields, structures and intrinsic viscosities of the polymers were compared with those of electroinitiated and solution decomposition methods. The characterization of the polymers was carried out using FTIR and 1H-NMR spectroscopies, differential scanning calorimetry and viscosity measurements. Optimum yield was obtained at 140 °C for a decomposition time of 24 hr. Polymerization proceeded through 1,2 and 1,4 additions taking place at the same time leading to a branched structure.

Electroinitiated polymerization of bis(4-bromo-2,6-dichlorophenoxo)N,N,N′,N′-tetramethylethylenediamine copper(II) complex

Abstract Electroinitiated polymerization of bis(4-bromo-2,6-dichlorophenoxo) N , N , N ′, N ′-tetramethylethylenediamine copper(II) complex was achieved upon oxidation. Prior to polymerization a cyclic voltammogram (CV) of the complex was obtained. Polymerization potentials were selected as the oxidation and reduction peak potentials of the complex, obtained by CV. Polymers in the form of poly(dihalophenylene oxide), were obtained by constant potential electrolyses carried out at redox peak potentials of the complex. No ligand or copper was found to incorporate into the final polymer product. The mechanism of polymerization was found to be free radicalic. It was also found that post-polymerization proceeds in the absence of current, when current is ceased after approximately 10 minutes of electrolysis. Percent conversions of polymerization had been measured by an electrochemical technique via simultaneous measurement of reacted monomer concentration. In order to follow the reacted monomer concentration by simultaneous CV measurement, a special H-type electrolysis cell with six electrodes was constructed. Polymers were characterized by 1 H-n.m.r., 13 C-n.m.r. and FT i.r. spectroscopy along with molecular weight measurements by the isopiestic method.

Polymerisation of bis(trichlorophenolato)tri(pyridine)nickel(II) and bis(trihalophenolato)di(pyridine)nickel(II) complexes in solid state

Abstract The synthesis of five-coordinated bis(trihalophenolato)tri(pyridine)nickel(II) and four-coordinated bis(trihalophenolato)di(pyridine)nickel(II) complexes from an aqueous solution and their characterisation by FT-IR, X-ray, DSC and elemental analysis is described. The thermal polymerisation of these complexes was carried out in the solid state and in the melt. Structural analyses were performed using 1 H NMR, 13 C NMR and FT-IR spectroscopic analyses. T g s were determined by differential thermal analysis and the molecular weights by viscometric method.

Polymerization of bis(4-bromo-2,6-dichlorophenoxo) ethylenediamine copper(II) complex by electro-initiation

Abstract Bis(4-bromo-2,6-dichlorophenoxo) ethylenediamine copper(II) complex has been polymerized using electro-initiation by constant potential electrolysis, in dimethylformamide-tetrabutylammonium fluoroborate solvent-supporting electrolyte couple, at room temperature under air or N2. The process leads to low molecular weight (5.6 × 103) linear poly(dichlorophenylene oxide). The structures of the polymers were determined by 1H-NMR and 13C-NMR. The kinetics of the polymerization were followed by in situ cyclic voltammetry measurements during electrolysis. Unlike thermal polymerization of this complex, the polymerization by electro-initiation begins immediately.

Electro-initiated polymerization of bis-(2,4,6-tribromophenoxo) ethylenediamine copper(II) complex in DMF and its kinetic study by cyclic voltammetry

Abstract The decomposition of bis-(2,4,6-tribromophenoxo) ethylenediamine copper(II) complex in dimethylformamide by electro-oxidation yields low molecular weight (4.5 × 10 3 ) linear poly(dibromophenylene oxide). Electro-initiated polymerization was accomplished upon oxidation by a constant potential electrolysis under air or under N 2 at room temperature. Polymerization conditions were based on the peak potentials measured by cyclic voltammetry. Constant peak potentials carried out at anodic and cathodic peak potentials yielded polymers in the anolyte only. The kinetics of the polymerization were followed by obtaining the unreacted monomer concentration by in situ cyclic voltammetry measurements during electrolysis. The characterization of the polymer was performed by 1 H-NMR, 13 C-NMR and FTIR spectroscopies. For determination of M n , the isopiestic method was used.

Free radical mediated interaction of ascorbic acid and ascorbate/Cu(II) with viral and plasmid DNAs

Previous studies indicate that ascorbic acid, when combined with copper or iron cleaves several viral DNA. ln this study, we generated the ascorbate radical anion electrochemically in a simple chemical environment without the participation of a metal ion. This solution possesses viral DNA scission activity. Ohe absence of catalytic metal ions [Fe (III) and Cu(II)] in the incubation medium was evidenced by metal chelating agents such as desferrioxamine and EDTA. Ohe radical quenching at high EDTA concentration was attributed to ionic strength of EDTA rather than metal chelation. Ohe effects of antioxidants, radical scavangers, catalase, superoxide dismutase and some proteins on DNA cleavage have been tested. Cleavage may not arise directly from ascorbate free radical but the reaction of the radical form of ascorbate with oxygen may produce the actual reactive species. Aerobic oxidation of ascorbate itself strictly requires transition metal catalysts, however electrochemically produced ascorbyl radical avoided the kinetic barrier that prevented direct oxidation of ascorbic acid with oxygen and eliminated the need for the transition metal ion catalysts.

Flame retardant alkyd paint

In this research long oil alkyd resin, and styrenated alkyd resin were made flame retardant by the incorporation of (i) bis-pyridine bis-tribromophenoxo copper (II) complex, and (ii) polydibromo-phenylene oxide (PDBPO). The former was synthesized in the laboratory, and the second one was obtained from the decomposition of the complex. Both of these compounds exhibit very good flame retardance effect when mixed with alkyd resins. Either of the additives is physically incorporated into the resins through grinding in a pebble mill until all particulates have a size below 10 μm. An oxygen index value of 26 was achieved with about 6% by weight PDBPO, and about 2% complex addition to the resins. These additives affect the physical and the mechanical properties of the paints when introduced at an amount of 8% either complex or PDBPO. The complex did not affect the drying time of resins while PDBPO increased the drying time of styrenated alkyd resin. Leveling and sagging are not affected in either case. The hardness was increased by the complex, and was not significantly changed by PDBPO. However the impact strength was decreased by either additive. The abrasion strength of long oil alkyd resin was decreased by PDBPO, and it was increased in all other cases.