Belkis Ustamehmetoğlu, Nesrin Köken, Nilgun Kizilcan, Ahmet Akar and Şebnem Tayyar
The purpose of this paper is to produce non-conductive copolymers of N-vinyl carbazole (NVCz) and methyl ethyl ketone formaldehyde resin (MEKFR) by the electroinduced Ce (IV…
Abstract
Purpose
The purpose of this paper is to produce non-conductive copolymers of N-vinyl carbazole (NVCz) and methyl ethyl ketone formaldehyde resin (MEKFR) by the electroinduced Ce (IV) polymerization method and the electrochemical oxidization of the formed copolymer to produce their conductive green form. The non-conductive and conductive copolymers were characterized by using Fourier transform infrared, solid-state conductivity and spectroelectrochemical, chronoamperometric, cyclovoltammetric and electrochemical impedance spectroscopic measurements.
Design/methodology/approach
The chronoamperometric electropolymerization of white, insulator form of the copolymer of NVCz and MEKFR (copolymer 1) on to Pt electrode was carried out and the green coloured film of the MEKFR-ox-NVCz copolymer (copolymer 11) was produced in the doped and conductive form. All reactions were performed in dichloromethane containing 0.1 M BU4NClO4. Copolymer 11 films obtained on the surface of the working electrode were removed and washed in acetonitrile and dried at room temperature before characterization. The results were compared with the copolymer obtained by electrochemical oxidation of MEKF-R and NVCz (copolymer 2).
Findings
The insulating copolymer of NVCz and MEKFR (copolymer 1) was produced by the electroinduced Ce (IV) polymerization method and converted into the conductive form electrochemically on the surface of the Pt electrode (copolymer 11). The polymers were characterized by electrochemical, spectrophotometric and conductivity measurements. The ionization potentials, optical band gap, peak potentials Ep, doping degree and specific capacitance of the copolymer 11 were obtained. The conductivity of the copolymer 11 is lower than the PNVCz and higher than the copolymer obtained by electrochemical oxidation of MEKF-R and NVCz (copolymer 2). The copolymer 11 has a lower onset potential than PNVCz and the copolymer 1 and slightly higher band gap than PNVCz. The capacitive behaviours of the copolymer 11 were very close to PNVCz.
Research limitations/implications
This study focuses on obtaining a green and conductive form of the copolymer of NVCz and MEKFR with the electrochemical method by using a white and insulator form of the same copolymer.
Practical implications
This work provides technical information for the synthesis of conducting copolymer of NVCz and MEKFR.
Social implications
These copolymers may be in the field of PNVCz applications such as photoconductivity and corrosion inhibition.
Originality/value
Electroinduced Ce (IV) MEKFR redox system was applied for the polymerization of NVCz monomer to produce the copolymer 1. The conductive copolymer 11 was synthesized through electrochemical oxidative coupling of the carbazole groups of the copolymer 1.
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Belkis Ustamehmetoğlu, Ahmet Akar, Nilgun Kizilcan and Eda Kelleboz
The purpose of this paper is to develop the soluble and processable conducting copolymers of carbazole (Cz), ethylcarbazole (ECz), N‐vinylcarbazole (NVCz) by oxidatively…
Abstract
Purpose
The purpose of this paper is to develop the soluble and processable conducting copolymers of carbazole (Cz), ethylcarbazole (ECz), N‐vinylcarbazole (NVCz) by oxidatively polymerising carbazoles by ceric ammonium nitrate (CAN) in the presence of methyl ethyl ketone formaldehyde resin (MEKF‐R); and to report the advantages of obtaining copolymer structure.
Design/methodology/approach
A new class of soluble and conductive P(Cz/MEKF‐R), P(NVCz/MEKF‐R) and P(ECz/MEKF‐R) copolymers were synthesised by the method of oxidative polymerisation with ceric ammonium nitrate. MEKF‐R, CAN and carbazole monomers (Cz, NVCz and ECz) were dissolved in acetonitrile separately. Then, the CAN solution was added dropwise into the mixture of MEKF‐R and Cz, NVCz or ECz solutions while stirring and a green powder was formed almost instantaneously. After one hour stirring at 25°C, the powder was filtered, washed with acetonitrile and dried at room temperature. A green coloured product was obtained. The colourless insulator copolymer present in this product was separated by selectively dissolving with toluene. The insoluble green copolymer was filtered off and dried at room temperature under vacuum. The products were characterised by FTIR, DSC thermograms, 1H‐NMR, four‐point probe conductivity and atomic absorption measurements.
Findings
The solubility and conductivity of the Cz/MEKF‐R copolymer P(Cz/MEKF‐R), the NVCz/MEKF‐R copolymer P(NVCz/MEKF‐R) and the ECz/MEKF‐R copolymer P(ECz/MEKF‐R) were regulated by the ratios of (Cz, NVCz, ECz)/CAN/MEKF‐R. By inclusion of the ketonic resin segments to the polycarbazole chains, thermally processable copolymers have been obtained with a melting point of about 80°C. FT‐IR results in different reaction time and the presence of metal in copolymers show together a complex between monomer‐metal and resin.
Research limitations/implications
This study focuses on obtaining conductive, soluble and processable copolymers. Since the ketonic resin is an insulator, in order to obtain both conductive and totally soluble polymer, successively regulating the ratios of (Cz, NVCz, ECz)/CAN/MEKF‐R is necessary.
Practical implications
This work provides technical information for the synthesis of conducting and totally soluble copolymer.
Originality/value
The conductive P(Cz/MEKF‐R), P(NVCz/MEKF‐R) and P(ECz/MEKF‐R) copolymers obtained by the method of oxidative polymerisation with ceric ammonium nitrate, which are totally soluble in DMF, could only be produced with this method and may increase the area of application of the carbazole polymers.
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Belkis Ustamehmetoğlu, Pelin Yazıcı and Nilgun Kızılcan
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…
Abstract
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 conductivity measurements and in situ spectroelectrochemical methods were performed for the characterization of polymers.
Findings
Carbazole‐9‐carbonyl chloride(CzCl) modified MEKFR was synthesised. This new carbazole‐modified resin (Cz‐MEKFR comonomer) has fluorescence property. The ionization potentials (Ip), electron affinity (Ea), optical band gap (Eg), peak potentials (Ep) and doping degree (y) of the polymers were calculated. Results were compared with the PCz homopolymer and the copolymer obtained from the mixture of MEKFR with carbazole P(Cz‐co‐MEKFR).
Research limitations/implications
This study focuses on obtaining a conductive polymer by using a fluorescence comonomer which is an insulator. In order to remove pyridine from comonomer, successively washing with several portions of dilute aqueous H2SO4, water‐saturated aqueous sodium hydrogen carbonate, and hot water is necessary.
Practical implications
This work provides technical information for the synthesis of fluorescence comonomer and conducting an alternative polymer.
Originality/value
A new Cz‐CFR comonomer was synthesised. This comonomer has a higher Tm value than MEKFR alone and also has fluorescence property. The band gap of the copolymer is not remarkably lower than polycarbazole. The oxidation potential of P(Cz‐MEKFR) was found to be higher than the PCz homopolymer and the solubility of copolymer is 30 per cent higher than homopolymer.
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Belkıs Ustamehmetoğlu, Nilgün Kızılcan and Ömer Demir
The purpose of this paper is to synthesise the block copolymer of pyrrole (Py) with bis(4‐inobutyl)polydimethylsiloxane (DA.PDMS) by electrochemical method. The characterisation…
Abstract
Purpose
The purpose of this paper is to synthesise the block copolymer of pyrrole (Py) with bis(4‐inobutyl)polydimethylsiloxane (DA.PDMS) by electrochemical method. The characterisation of the insoluble block copolymers, P(Py‐b‐DA.PDMS), was performed by cyclovoltammetric measurements, solid‐state conductivity and DSC measurements. The surface morphology of the copolymers was examined with scanning electron microscope (SEM).
Design/methodology/approach
Electropolymerisation process was performed potentiostatically and potentiodynamically. Redox behaviour of the resulting copolymer films was investigated. In‐situ spectroelectrochemical measurement was carried out on indium thin oxide (ITO) electrodes.
Findings
The ionisation potentials (Ip), electron affinity (Ea), optical band gap (Eg), peak potentials (Ep), and doping degree (y) of copolymers were calculated by using in‐situ spectroelectrochemical measurement results. The copolymers have slightly lower doping degree, band gap, Ip and Ea values than homopolymer. Copolymers had the conductivities of 10‐5 S/cm and had Tg values.
Research limitations/implications
This study can also be focused on obtaining conductive copolymer with insulator DA.PDMS blocks on the PPy chain by one‐step polymerisation.
Practical implications
This work provides technical information for the synthesis and characterisation of conducting block copolymer by electrochemical method.
Originality/value
Change in optical and electrical properties of the P(Py‐b‐DA.PDMS) shows the role of the individual properties of the copolymer blocks. While the DSC scan of PPy showed no transition temperature, which is a characteristic property of conducting copolymers, P(Py‐b‐DA.PDMS) had Tg values. This might be due to the inclusion of the DA.PDMS blocks on the PPy chains.