Belkıs Ustamehmetoğlu

Oxidative polymerization of N‐substituted carbazoles

Poly(N-vinylcarbazole), poly(N-carbazole) and poly(N-ethylcarbazole) powders were chemically synthesized by the reaction of ceric ammonium nitrate (CAN) with N-vinylcarbazole carbazole and N-ethylcarbazole in acetonitrile. Products were characterized by elemental analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and viscosity, X-ray fluorescence and four-probe conductivity measurement. It is found that when a suitable concentration of CAN is used in the polymerization process, the conductivity of chemically synthesized polymers can be improved further by controlling the CAN addition.

Electrochemical polymerization of pyrrole in acrylamide solution

Abstract Electrochemical polymerization of pyrrole (Py) in an excess of acrylamide (AAm) was accomplished by using an acetonitrile–tetraethyl ammonium perchlorate (TEAPC) solution containing both monomers. Characterization of soluble and insoluble products was carried out via FT-IR spectrum, cyclic voltammogram (CV), UV–visible spectrum, scanning electron microscope (SEM), differential scanning calorimetry (DSC) and elemental analysis. The role of monomer concentrations on the formation of resulting polymer was investigated. Since the polymerization rate of Py is faster than that of AAm, the appropriate ratio of concentrations of monomers have chosen to have chance to interact AAm with Py oligomers which was formed immediately on the electrode surface. Inclusion of AAm to polymer and the mole ratio of resulting product was reported.

An Electrochemical Study of Homopolymer, Copolymer and Composite Electrodes of Polypyrrole and Polycarbazoles

Abstract Copolymer and composites of pyrrole with carbazole were synthesized on a platin substrate and an electrochemical study of polymeric films was performed. The characterization of homopolymer, copolymer and composite films was performed by electrochemical methods (i.e., polarization curves and cyclovoltammetric measurements), morphological and elemental analyses, solid-state conductivity measurements and spectrophotometric methods comparatively. The reversibility of electrodes was checked by ferrocene in nonaqueous media. The stability of films was also tested both with corrosion and residual discharge capacity measurements in acidic aqueous solution.

Water-soluble polypyrroles by matrix polymerization : Interpolymer complexes

A new class of water-soluble polypyrroles (PPy) has been developed. This was accomplished by oxidative matrix polymerization of pyrrole (Py) monomer with Ce(IV) in the presence of poly(acrylic acid (PAA), poly(vinyl pyrrolidone) (PVP), and copolymers (CP) of vinyl pyrrolidone(VP) with acrylic acid (AA) [VP/AA; 25/75 ( CP 1 ), 50/50 ( CP 2 ), 75/25 ( CP 3 )]. The soluble and insoluble interpolymer complexes were observed according to the nature ( and conformation ) of polymers in mixture, the ratio of components, and the pH of solutions. The role of PAA, PVP, CP, Py, and Ce(IV) concentrations, the order of component addition, and the pH of the solutions were investigated. The evidence and structural reasons for the formation of soluble interpolymer complexes of PPy with different polymers are discussed. It is proposed that the compactization of the polymer matrix as well as the disturbance of the regularity of reactive groups on the polymer chain decreases the possibility of formation of soluble interpolymer complexes.

Interaction of metal ions with polypyrrole on polyacrylic acid matrix

The oxidative matrix polymerization of pyrrole (Py) by Fe(III), Cu(II), Ni(II), Co(II), and Zn(II) in the presence of polyacrylic acid (PAA) was studied and water-soluble products along with insoluble products were obtained. The metal (Me) content of the insoluble part was determined by using atomic absorption spectroscopy (AAS). The effects of the oxidation potential of Me ions and ligands on the aggregation of polypyrrole (PPy) on the matrix polymer were measured by ultraviolet (UV)-visible spectra. These findings also were checked by cyclic voltammetry (CV) measurements on PAA–Cu and PAA–PPy–Cu interactions. The conductometric titration results of PAA–PPy–Me ternary solutions were explained in the light of the interaction of Me ions with Py to polymerize on the PAA matrix resulting in some free carboxyl groups with a possibility of having Me–polymer complexes and a ternary complex (PAA–Me–PPy). The insoluble products were characterized by Fourier transform infrared (FTIR), elemental analysis, scanning electron microscopy (SEM), and four point probe conductivity measurements.

Determination of nitroaromatic and nitramine type energetic materials in synthetic and real mixtures by cyclic voltammetry.

Nitro-explosives contain reducible aromatic -NO2 groups or cyclic >N-NO2 bonds that may undergo reductive cleavage. This work reports the development of a cyclic voltammetric (CV) assay for nitro-aromatics (trinitrotoluene (TNT), dinitrotoluene (DNT)) and nitramines (1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)) using a glassy carbon electrode. This determination was first used for these energetic materials by resolving current responses of reduction potentials primarily due to one constituent but partly contributed by other constituents. Calibration curves of current intensity versus concentration were linear in the range of 30-120 mg L(-1) for RDX with a limit of detection (LOD) of 10.2 mg L(-1), 40-120 mg L(-1) for HMX (LOD=11.7 mg L(-1)), 40-120 mg L(-1) for TNT (LOD=11.2 mg L(-1)), and 40-140 mg L(-1) for DNT (LOD=10.8 mg L(-1)). Results showed that the CV method could provide a sensitive approach for the simultaneous determination of RDX and TNT in synthetic and real mixtures. Deconvolution of current contributions of mixtures at peak potentials of constituents was performed by multiple linear regression. The proposed method was successfully applied to the analysis of military explosives comp A5 and octol, and method validation was performed both against HPLC on a comp B (TNT+RDX) sample and against GC-MS on real post-blast residual samples containing both explosives.

Electroinduced polymerization of acrylonitrile in the presence of Ce(IV)

Polymerization of acrylonitrile (AN) initiated by Ce(IV) was performed in an electrolytic cell. The precipitated polymer was formed in the cathodic compartment, and the reduced initiator was reoxidized in the anode, thus allowing for the continuation of the process. The effects of concentrations of the monomer, Ce(IV), and sulfuric acid (the electrolyte) were investigated as well as the potential and the temperature. The yield of the process, proceeding under mild conditions, was high. The study was augmented by voltametric and spectrophotometric investigation. The resulting polymer was characterized by FTIR and optical spectrometry, and its m.w. was determined by viscometric method. A possible mechanism of polymerization is suggested.

Polymerization of cyclohexanone formaldehyde resin modified with carbazole‐9‐carbonyl chloride

Purpose – The purpose of this paper is to synthesise cyclohexanone formaldehyde resin (CFR)‐modified carbazole‐9‐carbonyl chloride (CzCl) via hydroxyl groups of CFR. This carbazole‐modified resin (Cz‐CFR) comonomer was characterised by common techniques such as UV, NMR, FTIR, fluorescence spectrophotometer, and scanning electron microscopy. The oxidative and electrochemical polymerisation of CzCl‐modified cyclohexanone formaldehyde resin (Cz‐CFR) were carried out.Design/methodology/approach – Cz‐CFR comonomer was synthesised by the esterification reaction of CzCl and hydroxyl groups of CFR. Then, for the chemical polymerisation, ceric ammonium nitrate (CAN)/DMF solution was added to the comonomer/DMF solution. The precipitate was filtered, washed with chloroform and dried. For the electrochemical polymerisation, potentiodynamic electrodeposition of Cz‐CFR comonomer in dichloromethane on to Pt was carried out.Findings – The concentration effect of CAN and Cz‐CFR on the conductivity, yield, solubility and T...

Polymerisation of methyl ethyl ketone formaldehyde resin modified with carbazole‐9‐carbonyl chloride

Purpose – The purpose of this paper is to obtain a conductive polymer by using a fluorescence comonomer which is an insulator. In this study, methyl ethyl ketone formaldehyde resin (MEKFR) modified with carbazole‐9‐carbonyl chloride (CzCl) was synthesised via hydroxyl groups of MEKFR. Electrochemical polymerisation of Cz‐MEKFR comonomer was carried out potentiostatically and a green, conductive polymer P(Cz‐MEKFR) was obtained. The advantages of obtaining alternative structure of P(Cz‐MEKFR) to the random copolymer were reported.Design/methodology/approach – Cz‐MEKFR comonomer was synthesised by the esterification reaction of CzCl and hydroxyl groups of MEKFR. Then, for the electrochemical polymerisation, potentiodynamic electrodeposition of Cz‐MEKFR comonomer in dichloromethane on to Pt was carried out. Electrochemical activities of polymers were tested by electrochemical methods (i.e. polarization curves and cyclovoltammetry). UV‐visible, NMR, polarization curves, cyclovoltammetric, solid‐state conducti...

Electrochemical Copolymerization of Pyrrole and Methyl Ethyl Ketone Formaldehyde Resin

ABSTRACT Electrochemical polymerization of pyrrole in the presence of methyl ethyl ketone formaldehyde resin (MEKF-R) was accomplished. Characterization of insoluble free-standing films was carried out via FTIR spectrum, cyclic voltammogram (CV), UV-visible spectrum, and four-point probe conductivity measurements. The effect of pyrrole and the resin concentrations on the conductivity of the resulting products was investigated. The copolymers obtained as free-standing films have conductivity value of 10−6–10−2 S/cm and they are insoluble in organic solvents.