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Öğe Brush-type surface modification of kapton with a new approach(Wiley, 2018) Vural, Sema; Seckin, TurgayIn 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.Öğe 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, TurgayPolyurethane (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.Öğe Nanometrik boyuttaki metal oksit sollerinin oluşumları, yapısal kontrolü ve fizikokimyasal özelliklerinin araştırılması(İnönü Üniversitesi, 2007) Vural, Sema[Abtsract Not Available]Öğe Pd Functionalized MCM-41 Catalysts for Suzuki Reactions(Springer, 2010) Gurbuz, Nevin; Vural, Sema; Yasar, Sedat; Ozdemir, Ismail; Seckin, TurgayPalladium (II) containing siliceous-MCM-41 has been prepared according to an original pathway by the reaction between silica precursors (imeo) and MCM-41. The resulting materials have been characterized by chemical analysis, X-ray powder diffraction, nitrogen sorption isotherms, and SEM and catalysis tests. Catalysis tests show that the very dispersive structure of the Pd-MCM-41 promotes the generation of fairly active catalysts for Suzuki cross-coupling of aryl chlorides and phenyl boronic acid under specific conditions, where the leaching of redox-active species has been minimized (less than 2 ppm).Öğe Poliimidler üzerine click kimyası uygulamaları(İnönü Üniversitesi, 2013) Vural, SemaBu tezin amacı, farklı polimer zincirleri aşılanmış fırça tipi polyimide filmlerin hazırlanması ve aydınlatılmasıdır. Klik tepkimesi bu tip fırça tipi polimerlerin hazırlanmasında başarılı olarak kullanıldı. Öncelikle, polyimide yüzey modifikasyonu, trimetilklorosilan ve çözgen olarak kloroform kullanılarak, klorometilasyon tepkimesi ile gerçekleştirildi. Daha sonar klorometil fonksiyonel polyimide yüzey azid fonksiyonel poliimidin hazırlanmasında kullanıldı. Aynı zamanda, polistiren, poli(metil metakrilat), poli(vinilprolidon), poli(metil akrilat) ve bu polimerlerin blok kopolimerleri gibi cliklenebilir polimerler, azid fonksiyonel poliimid yüzeye bağlanmak için ATRP tekniği ile sentezlendi ve bu kliklenebilir polimerler poliimid yüzeye bağlandı. Hazırlanan poliimidler ve kliklenebilir polimerler, FTIR, GPC, AFM ve SEM-EDX teknikleriyle yapısal olarak karakterize edildi., bozunma başlangıç sıcaklığı(ITD) ve yüzde kalıntı miktarı gibi diğer termal özellikler, aynı zamanda DSC, DTA ve TGA teknikleriyle belirlendi. Fırça tipi poliimidlerin, kliklenmiş polimer türüyle ilgili olan sıvı temas açısı, yüzey topolojisi, Tg ve termal kararlılık gibi fiziksel özellikler araştırılmıştır.Öğe Preparation and structural properties of Fe3O4-polyimide hybrid nanocomposites(Springer, 2010) Seckin, Turgay; Vural, Sema; Koytepe, SuleymanPolyimide films in which magnetic Fe3O4 nanoparticles are uniformly distributed are prepared. Before the preparation of the Fe3O4-polyimide composites, pure magnetite nanoparticles (Fe3O4) have been synthesized in water by co-precipitation (from ferric chlorides). Its surface was firstly modified with the 3-aminopropyl triethoxysilane. The prepared polyimide-Fe3O4 nanocomposite films were characterized for their structure, morphology, and thermal behavior employing Fourier transform infrared spectroscopy, scanning electron micrograph, X-ray diffraction, and thermal analysis (DTA/TGA/DSC) techniques.Öğe Preparation of the copper-based polyoxometalate/polyurethane composites and their dielectric properties(Sage Publications Ltd, 2020) Kucuk, Ilhan; Vural, Sema; Kivilcim, Nilufer; Adiguzel, Ibrahim; Koytepe, Suleyman; Seckin, TurgayThe aim of this study is synthesis of polyurethane (PU) composites from 4,4 '-methylenebis(cyclohexyl isocyanate), 1,2-ethanediol and different amounts of copper-based polyoxometalate (Cu-POM) and investigation of their dielectric properties. Firstly, Cu-POM structure as reinforcement was synthesized with ammonium heptamolybdate and Cu metal ion salt by a hydrothermal synthesis method. Then, Cu-POM-PU composites were prepared by in situ polymerization process. The prepared Cu-POM-PU composites were characterized by means of various techniques for their structure, morphology and thermal behaviour. The chemical structure, surface and morphological properties of the obtained composites were studied by Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) techniques. Thermal properties of these Cu-POM-PU composites were determined by thermogravimetric analysis, differential thermal analysis and differential scanning calorimetry analysis techniques. Dielectric properties of the Cu-POM-PU composites were also determined. The dielectric measured results showed that the dielectric constants decreased with the increase of the Cu-POMs content. The Cu-POM-PU composites showed relatively low dielectric constant compared to pure PUs.Öğe PVP-AŞILANMIŞ NiFe2O4 NANO PARÇACIKLARININ YÜZEY POLİMERİZASYONU TEKNİĞİ İLE SENTEZİ(Selçuk Üniversitesi Mühendislik Bilim ve Teknoloji Dergisi, 2018) Vural, Sema; Alphan, Aysel; Köytepe, Süleyman; Seçkin, TurgayÖz: Nikel ferrit nano parçacıkları, surfaktant destekli hidrotermal teknik kullanılarak, kontrollü parçacık boyutu ve boyut dağılımı ile sentezlenmiştir. Manyetik nano parçacıkların yüzey modifikasyonu (3-chloropropyl)triethoxysilane ile gerçekleştirilmiştir. Modifiye edilen nano parçacıklar yüzeyden başlatılan polimerizasyon tekniği kullanılarak PVP ile aşı polimer yapısında kaplanmıştır. Elde edilen spinel ferritlerin kristal yapısı ve boyutu X-Işını Kırınım Analizi (XRD) ve Taramalı Elektron Mikroskopu (SEM) ile araştırılmıştır. Nano parçacıkların ve nano kompozitlerin manyetik özellikleri Titreşimli Örnek Magnetometresi (VSM) kullanılarak incelenmiştir. Elde edilen NiFe2O4 nano parçacıklarının ortalama parçacık boyutu 24 nm’dir. Oda sıcaklığında süper paramagnetik karakter ve yüksek doygunluk manyetizasyonu göstermektedir. Gerçekleştirilen sentez stratejisinin biyouygulamalarda kullanılacak gelişmiş malzemelerin sentezinde etkili bir yöntem olabileceği düşünülmektedir.Öğe SPİNEL FERRİT NANO-PARÇACIKLARININ HİDROTERMAL SENTEZ TEKNİĞİ KULLANILARAK HAZIRLANMASI VE MANYETİK ÖZELLİKLERİNİN ARAŞTIRILMASI(Anadolu Üniversitesi Bilim ve Teknoloji Dergisi :A-Uygulamalı Bilimler ve Mühendislik, 2016) Vural, Sema; Alphan, Aysel; Köytepe, Süleyman; Seçkin, TurgayÖz: Son yıllarda biyoteknolojik uygulamalar içerisinde en çok tartışılan konular arasında genetik mühendisliği ve bu teknik ile elde edilen genetiği değiştirilmiş organizmalar yer almaktadır. Bu çalışmada üniversite öğrencilerinin genetiği değiştirilmiş organizmalar konusundaki bilincini ve bilgi düzeyini ölçmek amaçlanmıştır. Araştırmada veri toplama aracı olarak 22 sorudan oluşan bir anket formu kullanılmıştır. Araştırma evrenini İnönü Üniversitesi Gıda Mühendisliği ve Biyoloji bölümü lisans, yüksek lisans ve doktora öğrencilerinden oluşan 158 kişi oluşturmuştur. Öğrencilerin GDO hakkındaki bilgi ve görüşlerine yönelik değerlerin belirlenmesinde frekans (n) ve yüzde (%) değerleri kullanılmıştır. Elde edilen veriler bölüm ve cinsiyet değişkenleri açısından bağımsız gruplar t testi kullanılarak değerlendirilmiştir. Çalışma sonucunda öğrencilerin genelinin genetiği değiştirilmiş organizmalarla ilgili bilgi eksiklikleri olduğu ve genetik değişime yönelik olumsuz tutum sergiledikleri görülmüştür.Öğe Synthesis, characterization and dielectric properties of nickel-based polyoxometalate/polyurethane composites(Taylor & Francis Inc, 2019) Kucuk, Ilhan; Vural, Sema; Koytepe, Suleyman; Seckin, TurgayThe aim of this study was to synthesis, characterization and investigation of the influence of the polyoxometalate concentrations (1, 3, 5 and 10 wt%) on chemical, thermal, physical and morphological properties of nickel-based polyoxometalate/polyurethane composite (Ni-POM/PU) materials. Firstly, nickel-based polyoxometalate (Ni-POM) compound has been synthesized and characterized through various spectroscopic techniques. Synthesized Ni-POM compounds have been used for preparation of polyurethane composites as a reinforcement. Three different Ni-POM/PU composites containing Ni-POM were prepared by solution mixing and casting techniques. The chemical structure and morphology of prepared Ni-POWPU composite samples were confirmed by Fourier transform infrared spectroscopy (FTIR), elemental analysis and SEM techniques. Effects of Ni-POM on thermal stability, glass transition temperature, optical transparency, hydrophilicity and physical properties of polyurethane composites were examined. Thermal stabilities and glass temperatures of the materials have been checked by differential thermal analysis (DTA), thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). The SEM results confirmed the highly porous structure and the formation of Ni-POM structures in the polymer matrix. Synthesized composites showed high chemical stability, good processability, and low Tg values. The dielectric properties of the prepared Ni-POM/polyurethane composites were also investigated at room temperature. These results displayed that the dielectric constant of the POM/polyurethane composites decreased with the increase of the Ni-POM content in polymeric matrix. [GRAPHICS] .Öğe Synthesis, Characterization and Dielectric Properties of Rodlike Zinc Oxide-Polyimide Nanocomposites(Taylor & Francis Inc, 2012) Vural, Sema; Koytepe, Suleyman; Seckin, Turgay; Adiguzel, IbrahimNovel polyimide-rodlike zinc oxide hybrid nanocomposite (PI-RL-ZnO) has been developed from the poly (amic acid) with different weight percentages (1, 3, 5 wt%) of using N-methyl-2-pyrrolidone (NMP) and N, N-dimethylacetamide (DMAc) as aprotic solvents. The prepared zinc oxide-polyimide nanocomposites were characterized for their structure, morphology, and thermal behavior employing Fourier transform infrared spectroscopy (FTIR), scanning electron micrograph (SEM), transmission electron micrograph (TEM), X-ray diffraction (XRD) and thermal analysis (DTA/TGA/DSC) techniques. These studies showed the homogenous dispersion of zinc oxide in the polyimide matrix with an increase in the thermal stability of the composites on zinc oxide loadings. More importantly, we intend to explore the possibility of incorporating ZnO particles through dispersion into the polyimide network to achieve the polyimide hybrid with lower dielectric constant (low-k). The lowest dielectric constant achieved of the PI-RL-ZnO material is 2.82 by incorporating 5 wt% ZnO (pure PI, k = 3.22). The reduction in the dielectric constants of the PI-RL-ZnO hybrids can be explained in terms of creating ZnO particles and the free volume increase by the presence of the ZnO particles resulting in a loose PI structure.Öğe Synthesis, characterization, UV and dielectric properties of hexagonal disklike ZnO particles embedded in polyimides(Pergamon-Elsevier Science Ltd, 2011) Vural, Sema; Koytepe, Suleyman; Seckin, Turgay; Adiguzel, IbrahimA series of novel ZnO/polyimide composite films with different ZnO contents was prepared through incorporation hexagonal disklike ZnO particles into poly(amic acid) of the pre polymer of the polyimide. The hexagonal disklike ZnO particles with a diameter of 300-500 nm were synthesized from zinc acetate and NaOH in water with citric acid. The prepared zinc oxide-polyimide composites were characterized for their structure, morphology, and thermal behavior employing Fourier transform infrared spectroscopy, scanning electron micrograph, X-ray diffraction and thermal analysis techniques. Thermal analyses show that the ZnO particles were successfully incorporated into the polymer matrix and these ZnO/polymer composites have a good thermal stability. Scanning electron microscopy studies indicate the ZnO particles were uniformly dispersed in the polymer and they remained at the original size (300-500 nm) before immobilization. All composite films with ZnO particle contents from 1 to 5 wt% show good transparency in the visible region and luminescent properties. (C) 2011 Elsevier Ltd. All rights reserved.Öğe V2O5-polyimide hybrid material: synthesis, characterization, and sulfur removal properties in fuels(Springer, 2014) Erdogan, Selim; Koytepe, Suleyman; Seckin, Turgay; Onal, Yunus; Vural, Sema; Basar, Canan AkmilWe describe the synthesis of a new sorbent material for desulfurization of gasoline, which is composed of polyimide (PI) and vanadium pentoxide via the solution direct-dispersing method. The highly porous PI-V2O5 hybrid materials, containing different concentrations of V2O5 ranging from 1 to 10 wt%, were prepared from pyromellitic dianhydride, 2,4,6-triaminopyrimidine, and vanadium pentoxide. The produced PI-V2O5 composites were investigated by X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscope, and thermal analysis techniques. The effect of V2O5 on the sulfur removal properties as well as the thermal stability and porous structure of composites were investigated. Then the obtained material was investigated to determine their sorption characteristics for sulfur compounds from fuels. By use of this material, 91 wt% of the sulfur content was removed from sulfur-containing standard oil. An economic sensitive and simple method for the removal and separation of sulfur in fuel samples, using an PI-V2O5 packed mini chromatographic column, was established.
