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Amperometric Simultaneous Measurement of Copper and Cobalt Ions with Polythiophene Incorporating Pendant Terpyridine Groups
(Taylor & Francis Inc, 2014) Savan, Ebru Kuyumcu; Koytepe, Suleyman; Pasahan, Aziz; Erdogdu, Gamze; Seckin, Turgay
Terpyridine containing thiophene monomer was synthesized. Electrochemical behavior of the monomer was studied by cyclic voltammetry. This monomer was polymerized via electrochemical methods and the resultant polymer was characterized. The stepwise fabrication process of the polymeric film electrode and its electrochemical sensing performance towards simultaneously Co and Cu ions were evaluated. The sensing parameters of the polymer electrode were investigated in detail, and the determination conditions were optimized. Under the optimal conditions, sensor response peak is linear to the Co ion concentration in the range of 1.0-50.0 mu M and the Cu ion concentration in the range of 1.0-20.0 mu M. Detection limit of terpyridine-based polythiophene film electrode for Co and Cu is respectively 100 nM and 0.05 nM.
Boric Acid Containing Polyimide as a Route to Low Heat Releasing Materials
(Walter De Gruyter Gmbh, 2009) Koytepe, Sueleyman; Seckin, Turgay
Boric acid particles were successfully prepared by using an emulsion liquid membrane (water-in-oil-in-water, W/O/W emulsion) to control the size of particles as raw materials. All materials aggregated in aqueous suspension, but their subsequent dispersion on treatment with the polyimide precursor, poly (amic acid), was observed. Using a combination by dissolving the polyimide and mixing fatty acid surfactant coated boric acid particles; we have demonstrated the formation of nanocomposites with uniform nanoparticle dispersion. The influence of boric acid on heat releasing capacity was analyzed. Heat releasing capacity of composites was reduced compared to polyimide itself The microstructures and morphology of the as obtained samples were studied by X-ray diffraction (XRD), infrared spectra (IR), scanning electron microscopy (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS) and thermogravimetric analysis (TGA).
Brush-type surface modification of kapton with a new approach
(Wiley, 2018) Vural, Sema; Seckin, Turgay
In this study, polystyrene- and poly(methyl methacrylate)-grafted polyimide films were prepared successfully using click chemistry and the ATRP technique. Firstly, kapton films were prepared from stepwise thermal imidization of polyamic acid. Surface modification of kapton films was then achieved by chloromethylation followed by the azide decoration process. For surface grafting of kapton films, polystyrene and poly(methyl methacrylate) as alkyne functional polymers were prepared with alkyne and bromine double functionality using propargyl-2-bromopropionate as an initiator. A coupling reaction with azide-decorated PI surface and alkyne functional polymers was achieved via the Huisgen-1,3-dipolar cycloaddition reaction. FTIR spectroscopy, contact angle measurement, thermogravimetry (TG) and differential scanning calorimetry (DSC), energy dispersive X-ray analysis (EDX) and GPC techniques were used to characterize the grafted polyimides. According to the TG analysis, kapton film was modified at the rate of 8% and 10% with PS and PMMA, respectively.
Comparison dielectric and thermal properties of polyurethane/organoclay nanocomposites
(Elsevier, 2013) Baysal, Gulay; Aydin, Haluk; Koytepe, Suleyman; Seckin, Turgay
Polyurethane composites were obtained with different organoclay contents. The organoclay Na+-montmorillonite was dispersed in the PU matrix by mixing method from solution. Na+-montmorillonite was modified with dodecyl ammonium sulphate and 1-methyl-3-octyl imidazolium tetrafluoroborate. The nanocomposites obtained by using different modifier were compared in terms of dielectric and thermal properties. The dispersion state of the organoclay particles and its effect on the thermogravimetric and dielectric properties of the composites was investigated. The characterization of PU/organoocl ay composites was carried out by means of scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis and X-ray diffraction. The dielectric properties of the PU/organoclay nanocomposites were studied in detail. The obtained PU/organoclay intercalated nanocomposites exhibited better thermal stability and improved lower dielectric constants than the pure PU. (C) 2013 Elsevier B.V. All rights reserved.
Determination of characterization, antibacterial and drug release properties of POSS- based film synthesized with sol-gel technique
(Tubitak Scientific & Technological Research Council Turkey, 2021) Acari, Idil Karaca; Koytepe, Suleyman; Ates, Burhan; Yilmaz, Ismet; Seckin, Turgay
the study, antibacterial film synthesis was aimed using sol-gel technique from POSS structure with various functional groups. For this purpose, antibacterial properties have been acquired by metronidazole to the films to be synthesized. The films obtained were coated on glass surface samples by dip coating method. Antibacterial activities of surface coated glass samples were observed in E.coli and S. aureus bacteria. Metronidazole release studies in the film samples were followed by UV spectrophotometer. It was observed that drug release reached 68.90% at the end of the 24th h. As a result, it is thought that the synthesized film will be a good candidate especially for biomedical surface coating areas.
Development of voltammetric sensor based on polyimide-MWCNT composite membrane for rapid and highly sensitive detection of paracetamol
(Elsevier Sci Ltd, 2020) Burc, Muammer; Koytepe, Suleyman; Duran, Serap Titretir; Ayhan, Nurcan; Aksoy, Busra; Seckin, Turgay
In this work, for low level detection of paracetamol (PA) a voltammetric sensor was obtained. Polyimidemultiwall carbon nanotube (PI-MWCNT) composite film was used for modification of platinum (Pt) electrode as selective membrane. Firstly, this PI-MWCNT film was synthesized with 2,5-diaminopyridine (DAP), 4,4'-oxydiphthalic anhydride (ODPA) and MWCNT as a reinforcement by thermal imidization technique. The morphology, micro and chemical structures of the obtained composite film were studied by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and thermal analysis techniques. Then, the paracetamol sensor was prepared via the modification of Pt electrode with prepared PI-MWCNT composite film. Pt electrode was modified by coating with prepared PI-MWCNT composite film. Modified Pt electrode was used as PA sensor due to its selective membrane property in the presence of interfering substances for the electrochemical detection of PA. Electrochemical behaviour of paracetamol at the polyimide film modified Pt electrode was obtained by differential pulse voltammetry (DPV) and cyclic voltammetry (CV) method. It has shown that the modified electrode exhibits remarkable repeatability and precision in analytical paracetamol response as compared with other modified paracetamol electrodes. Comparing the responses of modified electrode with the unmodified Pt electrode, selectivity, sensitivity and stable responses significantly enhanced. A linear calibration plot having a correlation coefficient of 0.997 was obtained in the concentration range from 0.3 to 1.8 mM paracetamol. A linear calibration plot for low concentration area having a correlation coefficient of 0.999 was obtained in the concentration range from 0.002 to 0.05 mM paracetamol. Detection limit (LOD) and quantitative limit (LOQ) for paracetamol detection of PI-MWCNT modified electrode were calculated as 0.002 mM and 0.006 mM respectively. In addition, the presented method was applied for determination of PA in commercial tablets. The recovery efficiency of the PI modified electrode was obtained range of 96% and 102% for three different tablets. As a result; a simple, rapid, low cost, repeatable method showing good accuracy and precision (99.4%) has been developed for the selective and sensitive determination of paracetamol by prepared PI-MWCNT composite film modified electrode. (C) 2019 Elsevier Ltd. All rights reserved.
The effects of Zn and Yb co-dopants on the electronic, radiation shielding, structural, thermal and spectroscopic properties of hydroxyapatite
(Elsevier, 2024) Ayhan, Yasemin Merve; Ates, Tankut; Seckin, Turgay; Ozcan, Imren; Bulut, Niyazi; Kurucay, Ali; Kaygili, Omer
This work presents a comprehensive investigation of the electronic properties of hydroxyapatite (HA) doped with zinc (Zn) and ytterbium (Yb). Four different compositions, namely 0.33Zn-0.33Yb-HA, 0.33Zn-0.66Yb-HA, 0.66Zn-0.33Yb-HA, and 0.66Zn-0.66Yb-HA, were studied using Density of States (DOS) and band structure calculations. The computed band gap values for each composition were determined to be 4.3097 eV, 4.1324 eV, 4.2527 eV, and 4.2088 eV, respectively. The observed decrease in the band gap energy from 0.33Zn-0.33Yb-HA to 0.66Zn-0.66Yb-HA signifies a significant impact of the dopant composition on the electronic properties of the material. Furthermore, the inclusion of ytterbium in the HA matrix resulted in the formation of a distinct band and peak in the density of states. This indicates the emergence of specific energy levels associated with Yb, suggesting a distinct influence on the electronic structure of the material. These findings provide valuable insights into the tunability of the electronic properties of HA through controlled doping with Zn and Yb. Such knowledge is crucial for tailoring materials with desired electronic characteristics, thus holding promise for various applications in electronic devices and biocompatible coatings. The as-modeled structures were synthesized via a wet chemical route. Fourier transform infrared (FTIR), Raman, and X-ray diffraction (XRD) analyses verified the formation of the HA structure for each sample. Differential thermal analysis (DTA) results showed that all the as-prepared samples were thermally stable. The negligible mass losses were detected for all the samples in the thermogravimetric analysis (TGA) measurements. The addition of both co-dopants affected crystal structure related parameters and decreased the crystallinity and cell viability.
An experimental and theoretical investigation of the structure of synthesized ZnO powder
(Elsevier Science Bv, 2018) Kaygili, Omer; Ercan, Ismail; Ates, Tankut; Keser, Serhat; Orek, Cahit; Gunduz, Bayram; Seckin, Turgay
ZnO powder has been synthesized, characterized experimentally and its theoretical modeling carried out by density functional theory (DFT). The experimental and theoretical results were compared with each other and with the available data in the literature. A detailed crystal structure analysis was carried out using X-ray diffraction (XRD) data. Experimental and theoretical FTIR analysis, energy gap and density of states and electronic band structure calculations have been done for a complete characterization of the material. The surface morphology has been investigated by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. It has been found that the electron excitation of ZnO can occur most probably at the Gamma-Gamma point, where the energy gap has the lowest value between the valance and conduction bands.
Ferrocene Containing Polyimides as a Route to Low-? Dielectric Materials
(Wiley-V C H Verlag Gmbh, 2010) Seckin, Turgay; Koytepe, Suleyman; Kivilcim, Nilufer
Polyimides incorporating the ferrocene unit were prepared by in situ curing of poly (amic acid) macromolecules with ferrocene, for the molecular-level design of low dielectric constant (low-kappa) materials. The effects of ferrocene on dielectric properties of polyimide are investigated in detail in this study. Ferrocene containing polyimides exhibit a number of desirable properties including low-water absorption and admirable thermal stability. Systematic studies demonstrate that proper insertion of ferrocene into a polyimide backbone can give rise to a reduction in the material's dielectric constant. All composites were subjected to DSC measurements for the purpose of examining Tg from all composition. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and the other conventional techniques were used for structural characterization.
Fructose-Based Polyurethane Membranes: Synthesis, Characterization, and Their Use as Voltammetric pH Electrode
(Taylor & Francis As, 2015) Gungor, Oznur; Pasahan, Aziz; Cengiz, Mahmut Alper; Koytepe, Suleyman; Seckin, Turgay
In this study, polyurethane films prepared from the 4,4-diphenylmethane diisocyanate (MDI), ethylene glycol, and different ratio fructose were used to prepare a novel amperometric pH electrode. Fructose-based films were characterized by FT-IR, DSC, DTA, and TGA. Prepared polyurethanes exhibited suitable T-g(degrees C), good thermal stability and good adhesive properties. The incorporation of saccharides into the PU structure results in a higher crosslinking density and a higher content of hard segments. Furthermore, the behavior of films prepared from polyurethane solutions containing 1%, 3%, 5%, and 10% fructose toward pH changes were examined by normal pulse voltammograms technique and diferantial pulse voltammetry. [GRAPHICS] .
Hydrothermal Synthesis of Polyoxometalate Containing Cobalt Ion, and Its Polyurethane Composites for Dielectric Material Applications
(Taylor & Francis Inc, 2020) Kucuk, Ilhan; Vural, Sema; Kivilcim, Nilufer; Adiguzel, Ibrahim; Koytepe, Suleyman; Seckin, Turgay
Polyurethane (PU) composites were prepared with different diisocyanate and diol compounds by adding cobalt ion-based polyoxometalate (Co-POM) as reinforcement. For the determination of using potential in microelectronic applications, the dielectric behavior and dielectric constant of these PU composites were investigated and compared to pure polyurethane structures. For this aim, firstly, Co-POM with Keggin structure was obtained from ammonium heptamolybdate, 1,10-phenanthroline ligand and a cobalt (II) salt by hydrothermal synthesis technique. Then, polyurethane/Co-POM composites (PU/Co-POM) were prepared with ethylene glycol, nonaromatic diisocyanate and different amounts of Co-POM reinforcement (1%, 3%, 5% and 10%, w/w) by in situ polymerization and mix-blend technique. Obtained PU/Co-POM composites were characterized in detail by infrared spectroscopy, Elemental Mapping, Energy-dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (XRD) spectroscopy. The surface structure, morphology and roughness of PU/Co-POM composites were investigated by SEM and AFM analysis. The elemental maps of the PU/Co-POM surface were examined by EDX elemental mapping analysis methods. Thermal stability, Tg values and thermal decomposition temperatures of PU/Co-POM structures were determined by different thermal analysis techniques. Thermal analysis results showed that the PU/Co-POM composites are thermally stable up to approximately 200 degrees C and Tg values of synthesized PU composites are seen between 54.72 degrees C and 75.15 degrees C. The dielectric properties and dielectric constants of the PU/Co-POM composites were determined in the frequency range 1 Hz to 1000 kHz at room temperature using impedance analyzer. Dielectric constants of these composites were ranged from 5.50 to 9.26 according to their polarizability and H-bonding ability of PU matrix structure. According to the dielectric measurements, the dielectric constants of the PU/Co-POM structures were significantly decreased compared to the pure PU structures.
In Situ Preparation of Polyether Amine Functionalized MWCNT Nanofiller as Reinforcing Agents
(Hindawi Ltd, 2014) Yildrim, Ayber; Seckin, Turgay
In situ preparation of polyether amine functionalized cross-linked multiwalled carbon nanotube (MWCNT) nanofillers may improve the thermal and mechanical properties of the composites in which they are used as reinforcing agents. The reduction and functionalization of MWCNT using ethylenediamine in the presence of polyether amine produced stitched MWCNT's due to the presence of two amine (-NH2) functionalities on both sides of the polymer. Polyether amine was chosen to polymerize the carboxylated MWCNT due to its potential to form bonds with the amino groups and carboxyl groups of MWCNT which produces a resin used as polymeric matrix for nanocomposite materials. The attachment of the polyether amine (Jeffamine) groups was verified by TGA, FT-IR, XRD, SEM, and Raman spectroscopy. The temperature at which the curing enthalpy is maximum, observed by DSC, was shifted to higher values by adding functionalized MWCNT. SEM images show the polymer formation between MWCNT sheets.
Low Dielectric Constant Polyimide-Zirconium Nanocomposites with Improved Thermal Properties
(Taylor & Francis As, 2008) Seckin, Turgay; Koytepe, Suleyman; Kivilcim, Niluefer; Bahce, Erkan; Adiguzel, Ibrahim
Low-dielectric-constant (kappa) polyimide films with thermal integrity and controllable mechanical strength have been prepared by covalently bonding zirconium complex with lysine to the main chains of polyimide. The presence of chemical bonds between polyimide (PI) and zirconium has great effect on the properties of polyimide films, especially on their thermal and dielectric properties. The dielectric constants of the resultant nanocomposites are lower due to the increased free volume and fewer polar Zr-O-Zr groups, and can be tuned by varying the molar ratio of zirconium(IV) propoxide, Zr(OPr)(4), in the feed. The possibility of obtaining the kinetic parameters of a reaction from a heating rate dependence of DTA peak location, as well as the merits of different peak methods, were also discussed. The composition, particle sizes, and morphological effect of the Zirconium on nanoparticles were determined by the energy dispersive analysis of X-ray (EDAX), and scanning electron micrographs (SEM).
Maltose-Containing Polyurethane Films: Synthesis, Characterization, and Their Use for Determination of Dopamine in the Presence of the Electroactive and Nonelectroactive Interferents
(Taylor & Francis As, 2013) Pasahan, Aziz; Koeytepe, Sueleyman; Cengiz, M. Alper; Seckin, Turgay
A series of polyurethanes were prepared from the maltose-ethylene glycol-diphenylmethane diisocyanate and used to construct a novel polyurethane electrode for the detection of dopamine. The polyurethanes were characterized by FT-IR, differential scanning calorimetry, and thermogravimetric analysis. The intrinsic viscosity and adhesive properties were also evaluated. Selectivity behaviour of films prepared from polyurethane solutions containing 1%, 3%, 5%, and 10% maltose to electroactive and nonelectroactive substances was examined by DPV. The results demonstrated that polymer electrode by 2 mu L polyurethane solutions containing 3% maltose was allowed penetration of dopamine while blocking the permeation of ascorbic acid and uric acid through film.
Metallo-supramolecular materials based on terpyridine-functionalized polyhedral silsesquioxane
(Wiley, 2014) Koytepe, Sueleyman; Demirel, Maruf Hursit; Gultek, Ahmet; Seckin, Turgay
In this study, novel metallo-supramolecular materials based on terpyridine-functionalized polyhedral silsesquioxane were synthesized from 4 '-chloro-2,2 ':6 ',2 ''-terpyridine and amino-group-functionalized polyhedral oligomeric silsesquioxane. The obtained terpyridine-functionalized polyhedral silsesquioxanes were converted to metallo-supramolecular hybrid materials by coordination polycondensation reaction with Co(II) or Cu(II) ions. The supramolecular polymers created were characterized by means of structure, morphology and stimuli-responsive performance employing scanning electron microscopy, amperometric techniques and UV-visible and Fourier transform IR spectroscopy. UV-visible and cyclic voltammetry studies showed that both the optical and electrochemical properties of metallo-supramolecular materials are affected by the substituent at the pyridine periphery. The supramolecular polymers obtained exhibited electrochromism during the oxidation processes of cyclic voltammogram studies. As a result, these terpyridine-functionalized polyhedral silsesquioxanes are good candidates for electronic, opto-electronic and photovoltaic applications as smart stimuli-responsive materials. (c) 2013 Society of Chemical Industry
Molecular design of Fe3O4-containing polyimide as a route to nanomagnetic materials
(Amer Chemical Soc, 2008) Koeytepe, Suelleyman; Seckin, Turgay
gamma-Fe3O4 doped polyirnide films with different weight percentages (1, 5, and 10 wt % of Fe3O4) have been prepared and the effect of nonmagnetic gamma-Fe3O4 content on the structural and magnetic properties has been studied. X-ray diffraction (XRD) studies revealed that the nanopowders obtained are magnetite. The calculated grain sizes from XRD data have been verified using scanning electron microscopy (SEM). SEM micrographs show that the powders consist of nanometer-sized grains. Magnetic hysteresis loops were measured at room temperature with a maximum applied magnetic field. As the gamma-Fe3O4 content increases, the measured magnetic hysteresis curves become more and more narrow and the saturation magnetization and remanent Magnetization both decreased. The prepared nanocomposites were identified in terms of their structure, morphology, and magnetic and thermal properties. These studies showed that the particles seem to be dispersed randomly, although the particles do appear to form aggregates at increasing particle loadings.
Molecular design of nanometric zinc borate-containing polyimide as a route to flame retardant materials
(Pergamon-Elsevier Science Ltd, 2009) Koytepe, Suleyman; Vural, Senia; Seckin, Turgay
Zinc borate (Zn2B6O11 center dot 3H(2)O) nanoparticles were successfully prepared by using an emulsion liquid membrane (W/O/W emulsion) to control the size of particles with Na2B4O7 center dot 10H(2)O, boric acid and ZnSO4 center dot 7H(2)O as raw materials. All materials were dispersed with the polyimide (PI) precursor, poly (amic acid). Using a combination of dissolving the poly (amic acid) and mixing fatty acid surfactant-coated zinc borate nanoparticles: we have demonstrated the formation of nanocomposites with uniform nanoparticles dispersion. We report the first deposition of namocomposite polyimides from solution using spin-coating. The microstructures and morphology of the as-obtained samples were studied by Xray diffraction (XRD), infrared spectra (IR), scanning electron microscopy (SEM) equipped with an energy-dispersive X-ray spectrometer (EDX), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). (C) 2008 Elsevier Ltd. All rights reserved.
Molecular design of POSS core star polyimides as a route to low-? dielectric materials
(Elsevier Science Sa, 2008) Seckin, Turgay; Koeytepe, Sueleyman; Adiguezel, H. Ibrahim
Star polyimides incorporating the polyhedralsilsesquioxane (POSS-NH2) unit were prepared by in situ curing of polyamic acid macromolecules with amino POSS, octa (aminopropylsilsesquioxane), for the molecular-level design of low dielectric constant (low-kappa) materials that can be used to manufacture integrated circuits. Octameric POSS-NH2 having restricted rotation by multiple point attachment to the polyimide backbone is shown to introduce free volume into the films, thereby lowering their dielectric constants. A process for synthesizing POSS-polyimide star nanocomposites is reported, comprising a step forming porous-type POSS and subsequent step with polyimide precursor. The POSS-NH2 containing polyimides exhibit a number of desirable properties including low-water absorption and high thermal stability. Systematic studies demonstrate that proper insertion of POSS into a polyimide backbone can give rise to a reduction in the material's dielectric constant while also improving its mechanical and thermal properties. (C) 2008 Elsevier B.V. All rights reserved.
Novel assemblies of Sn(II) coordinated polyimide supported by a ligand containing N-Heterocyclic phenantroline unit
(Springer, 2008) Koytepe, Suleyman; Gurbuz, Nevin; Ozdemir, Ismail; Seckin, Turgay
The purpose of this work is to investigate the possibility of the production of novel metal coordinated polyimides. This research primarily focuses on novel metal complex assemblies of Sn(II) linked to the polymer molecule by a ligand containing an N-heterocyclic phenantroline unit in the main chain. Polyimide with phenantroline units in the main chain was synthesized utilizing condensation polymerization of aromatic dianhyrides and the bis(5-aminophenantroline)dichlorotin(II) to yield metal coordinated polyimides. Characterization by thermal analysis, refractive index, and dielectric analysis revealed distinct differences between these new materials and the classical polyimides.
A novel electrochemical biosensor based on polyimide- boron nitride composite membranes
(Taylor & Francis As, 2017) Aksoy, Busra; Pasahan, Aziz; Gungor, Oznur; Koytepe, Suleyman; Seckin, Turgay
Polyimide (PI) and polyimide-boron nitride (PI-BN) composites as dopamine-selective membrane were synthesized. The structures of the monomer, pure PI, and PI-BN composites were characterized by FT-IR, SEM, and thermal analysis techniques. Experiment results showed that introduction of BN particles increased porosity, selectivity and improved heat-resistance of polyimide matrix. Selectivity of PI-BN composite membranes toward dopamine and interferences was examined by DPV technique. Electrochemical measurement results illustrated that polyimide membrane containing 5% BN possessed wide linear ranges, excellent sensitivity, selectivity, reversibility, and low detection limits (4 X 10(-8) M). The polyimide membrane was very high R value (0.9904). [GRAPHICS] .

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