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Öğe Facile preparation of gold nanoparticles on the polyquinoline matrix: Catalytic performance toward 4-nitrophenol reduction(Elsevier Science Sa, 2015) Bilici, Ali; Ayten, Bahar; Kaya, İsmetGold nanoparticles (AuNPs) have been introduced into polyquinoline (PAQ) matrix for the first time. For this purpose, 5-amino quinoline (AQ) and auric acid solution were used as a monomer and oxidant, respectively. Incorporation of gold nanoparticles into the PAQ matrix led to improved thermal stability: 5% of product was decomposed at 643 degrees C. Photoluminescence characteristics of resulting composite (Au@PAQ) were determined. Au@PAQ was also successfully utilized for the catalytic reduction of 4-nitro phenol (4NP) to 4-amino phenol (4AP). The reduction process was completed in only four minutes at 25 degrees C. Pseudo-first-order rate constant was estimated to be 3.05 x 10(-3)s(-1). The results were compared with the previous reported ones. (C) 2015 Elsevier B.V. All rights reserved.Öğe İmin bağı içeren hidrojellerin sentezi ve karakterizasyonu(Çanakkale Onsekiz Mart Üniversitesi, 2016) Ayten, Bahar; Kaya, İsmetSunulan tez çalışmasında 2FHK ve 2,7DHN bileşiklerinin asidik çözeltide kitosan template varlığında oksidatif polimerleşmesi ve aynı zamanda kitosanın glutaraldehit ile çapraz bağlanmasıyla oluşan hidrojellerin sentezi ve karakterizasyonu incelendi. Reaksiyon ortamında kitosan template olarak hava ise oksidant olarak kullanıldı. Kitosan template içerisinde polimerleşen dihidroksi polimerleri ile kitosan hidrojen bağı ile çapraz bağlandı. Artan çapraz bağlanma ile viskozitenin arttığı gözlendi. Değişik oranlarda glutaraldehit çapraz bağlayıcısı da kitosan ve glutaraldehit arasında imin bağı oluşturmak için çapraz bağlayıcı olarak kullanıldı. Kitosan hem hidrojen bağı hemde kovalent bağlarla çapraz bağlanarak hidrojel sentezlendi. Sentezlenen hidrojellerin karakterizasyonu FT-IR, TG, SEM, CV analizleri ile yapılmıştır. Sentezlenen tüm hidrojellerin şişme davranışları süreye göre incelendi. Dihidroksi bileşiklerinin asidik kitosan çözeltisi içinde polimerleştiğini karakterize etmek için kitosan NaNO2/HCl kullanılarak depolimerize edildi ve hidroksi polimeri reaksiyon ortamından uzaklaştırıldı. Ayrıca dihidroksi bileşikleri alkali ortamda NaOCl kullanılarak polimerleştirildi ve iki yöntemle elde edilen hidroksi polimerlerinin FT-IR, UV-Vis, 1H NMR ve GPC analizleri yapılarak sonuçlar karşılaştırıldı.Öğe Syntheses of poly(phenoxy-imine)s anchored with carboxyl group: Characterization and photovoltaic studies(Elsevier, 2018) Kaya, İsmet; Ayten, Bahar; Şenol, DilekA serious of pyridine based Schiff bases (M1, M2, and M3) were synthesized via condensation reaction of 4-aminosalicyclic acid with 2-pyridinecarboxaldehyde, 3-pyridine carboxyaldehyde and 4-pyridinecarboxaldehyde, respectively. The transformation of Schiff bases into their poly(phenoxyimine) species (P1, P2, P3) was obtained using oxidative polycondensation (OP) by NaOCl as the oxidant in alkaline medium at 70 degrees C. The structures of the synthesized compounds were characterized by solubility test, FT-IR, UV-Vis and NMR techniques. Thermal data were obtained by TG-DTA and DSC techniques. Photoluminescence (PL) properties of the synthesized materials were examined in organic solvent. Fluorescence measurements were carried out in various concentrated solutions to determine the optimum concentrations and PL intensities. P3 could be used in light-emitting diodes due to its multi-color (white, blue, green and yellow) light-emitting property. The efficiency (eta) of a solar cell of P1, P2 and P3 were determined by single channel Potentiostat/Galvanostat with electrochemical impedance spectroscopy. The order of conductivities was found to be as P3>P2>P1 as a result of iodine doping. The best performing photovoltaic cell with I-sc (mA cm(-2)), V-oc (V), FF, and eta (%) as -0.642, 0.399, 0.461 and 0.118 was obtained for P3. (C) 2018 Elsevier B.V. All rights reserved.Öğe Synthesis and electrochemical properties of chitosan-polyphenol composites(Elsevier, 2020) Kaya, İsmet; Ayten, Bahar; Yaşar, Alper ÖmerA unique series of chitosan-polyphenol composites with superior electrochemical properties, chitosan/poly(2-phenyl hydroquinone) (Ch/PPHQ) and chitosan/poly(2,7-dihydroxy naphthalene) (Ch/PDHN) were synthesized with the phenolic derivates, 2-phenyl hydroquinone (PHQ) and 2,7-dihydroxy naphthalene (DHN) in the presence of chitosan (Ch) biopolymer as a tempate. The synthesized Ch/PPHQ and Ch/PDHN composites were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), thermal gravimetric (TG) analysis and their behavior of swelling in the distilled water. Moreover, poly(2-phenyl hydroquinone) (PPHQ) and poly(2,7-dihydroxy naphthalene) (PDHN) were synthesized using PHQ and DHN by oxidative polymerization technique. The synthesized polymers were also characterized by the gel permeation chromatography-light scattering (GPC-LS), ultraviolet-visible (UV-vis) spectroscopy, proton nuclear magnetic resonance (H-1 NMR) spectroscopy, and carbon nuclear magnetic resonance (C-13 NMR) spectroscopy. The M-n and M-w values of the synthesized polymers were obtained in the range of 3.4 and 34.7 kDa. The M-n and M-w values of PPHQ are approximately 2.5-fold higher than the M-n and M-w values of PDHN. Additionally, The M-n and M-w values of PPHQ and PDHN are 1.5-2.5 times higher than the PPHQ* and PDHN* synthesized in Ch matrix. The prepared Ch/PPHQ and Ch/PDHN composites are redox-active materials. The E-HOMO and E-LUMO values of PPHQ, Ch/PPHQ, PDHN, and Ch/PDHN materials were calculated in the range of -4.95 to -5.36 eV and - 3.01 - 3.53 eV by measuring the oxidation (E-ox) and the reduction (E-red) potential values by the cyclic voltammetry (CV). Moreover, the E-g values of PPHQ, Ch/PPHQ, PDHN, and Ch/PDHN were calculated in the range of 1.54-2.14 from the obtained E-HOMO and E-LUMO values. It is seen that Ch/PPHQ and Ch/PDHN composites have lower E-g values than PPHQ and PDHN. According to these results, it can be attributed that Ch/PPHQ and Ch/PDHN composites have preferable electrochemical properties by comparison with the PPHQ and PDHN.
