Arslan, Hülya | Yeşilyurt, Nazı | Hazer, Baki

Article | 2007 | JOURNAL OF APPLIED POLYMER SCIENCE106 ( 3 ) , pp.1742 - 1750

https://dx.doi.org/10.1002/app.26870 https://hdl.handle.net/20.500.12628/3681

Wadhwa, Sham Kumar | Tüzen, Mustafa | Kazi, Tasneem Gul | Soylak, Mustafa | Hazer, Baki

Article | 2014 | Food Chemistry152 , pp.75 - 80

A new adsorbent, polyhydroxybutyrate-b-polyethyleneglycol, was used for the separation and preconcentration of copper(II) and lead(II) ions prior to their flame atomic absorption spectrometric detections. The influences of parameters such as pH, amount of adsorbent, flow rates and sample volumes were investigated. The polymer does not interact with alkaline, alkaline-earth metals and transition metals. The enrichment factor was 50. The detection limits were 0.32 µg L-1 and 1.82 µg L-1 for copper and lead, respectively. The recovery values were found >95%. The relative standard deviations were found to be less than 6%. The validat . . .ion of the procedure was performed by analysing certified reference materials; NIST SRM 1515 Apple leaves, IAEA-336 Lichen and GBW-07605 Tea. The method was successfully applied for the analysis of analytes in water and food samples. © 2013 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Gökçen, Muharrem | Yıldırım, Mert | Demir, Ahmet | Allı, Abdulkadir | Allı, Sema | Hazer, Baki

Article | 2014 | Composites Part B: Engineering57 , pp.8 - 12

Au/poly(propylene glycol)-b-polystyrene/n-Si (D1) and Au/poly(propylene glycol)-b-polystyrene(HAuCl4 dispersed)/n-Si (D2) diodes were fabricated and their response to UV illumination was investigated using current-voltage measurements in dark and under various illumination intensities (50-250 mW/cm2). Scanning Electron Microscope micrographs of the diodes were provided for morphological analysis. Main electrical parameters; such as ideality factor, barrier height and reverse saturation current, are calculated using Thermionic Emission and Norde's method, and it was found that they show dependence on UV illumination. Ideality factor . . .values of D1 and D2 diodes in dark is 2.53 and 2.29 whereas they are 3.37 and 3.39 under 100 mW/cm2 UV illumination, respectively. A noticeable effect of UV illumination is the considerable increase of current in the reverse bias region compared with current in dark such that current value increases by ~10 3 times with 100 mW/cm2 UV illumination for both diodes. Furthermore, density distribution profiles of surface states in these diodes were also investigated. © 2013 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Hazer, Baki | Eren, Melike

Article | 2019 | JAOCS, Journal of the American Oil Chemists' Society96 ( 4 ) , pp.421 - 432

Ecofriendly autoxidation is a reaction of air oxygen with unsaturated organic molecules at room temperature. Castor oil and ricinoleic acid were ecofriendly autoxidized for 5 months to obtain castor oil macroperoxide with a Mn of 1935 g mol -1 (Pcast5m) and the ricinoleic acid macroperoxide initiator (Prici5m) with a Mn of 1169 g mol -1 . Peroxide groups thermally initiated the free radical polymerization of methyl methacrylate (MMA), n-butyl methacrylate (nBMA), and styrene (S). Peroxide formation in the oxidized castor oil and ricinoleic acid was confirmed using iodometric analysis, elemental analysis, and differential scanning ca . . .lorimetry technique. Peroxide decomposition in both macroperoxide initiators was observed at 166 °C for Prici5m and 170 °C for Pcast5m. Hydroxyl groups of Pcast5m were reacted with methacryloyl chloride to obtain methacrylated castor oil macroperoxide (PcastMA). The polymerization rates of the obtained macroinitiators were compared. The polymerization rate order is Pcast5m > Prici5m > PcastMA. Polymerization of styrene by PcastMA resulted in an increase in molar masses and an increase in the polymerization time while those of the styrene polymerization by Pcast5m and Prici5m remained constant. Carboxylic acid groups were reacted with amine-terminated polyethylene glycol (PEG), polydimethyl siloxane (PDMS), and polytetrahydrofuran (PTHF) while the hydroxyl functionality initiated the ring-opening polymerization of ?-caprolactone (CL). Prici-PEG-PMMA, Prici-PS-PDMS, Prici-PS-PTHF, Pcast-PS-PCL, Pcast-PCL-PMMA, and Pcast-PS-PnBMA multiblock copolymers were prepared and characterized using spectrometric, thermal, and stress–strain measurement techniques. © 2019 AOC Daha fazlası Daha az

Erduranlı, Haydar | Hazer, Baki | Borcaklı, Mehlika

Conference Object | 2008 | Macromolecular Symposia269 ( 1 ) , pp.161 - 169

Chemical modification is useful to diversify poly(3-hydroxyalkanoate)s, for medical and industrial applications. In this manner, transesterification reactions of poly(3-hydroxy butyrate) were carried out under reflux condition of 1,2-dichlorobenzene in the presence of 1,4-butane diol, poly(ethyleneglycol) bis(2-aminopropyl ether) with molecular weights of 1000 and 2000, poly(ethylene glycol)methacrylate or glycerol at 180°C. Addition reactions of bromine and -SH groups of 3-mercaptopropionic acid to the double bond of poly(3-hydroxy-io-undecenoate) were also carried out. Functionalized poly(3-hydroxyalkanoate)s were characterized us . . .ing 1H NMR, FTIR, GPC and thermal analysis techniques. Copyright © 2008 WILEY-VCH Verlag GmbH & Co. KGaA Daha fazlası Daha az

Bayramoğlu, Gülay | Hazer, Baki | Altıntaş, Begüm | Arıca, M. Yakup

Article | 2011 | Process Biochemistry46 ( 1 ) , pp.372 - 378

In this study, a functionalized hydrophobic polypropylene chloride membrane (PPC) was prepared by the amination of chlorinated polypropylene with hexamethylene diamine (APP). The PPC and APP membranes were characterized using SEM, FTIR and contact angle studies. The aminated polypropylene (APP) membrane was used for covalent immobilization of Candida rugosa lipase via glutaraldehyde coupling. The retained activity of the immobilized lipase was 76%. Kinetic analysis shows that the dependence of lipolytic activity of both free and immobilized lipase on tributyrin substrate concentration can be described by Michaelis-Menten model. The . . .estimated apparent Km values for the free and immobilized lipase were 2.9 and 8.4 mM, respectively. The Vmax values of free and immobilized enzymes were calculated as 926 and 741 U/mg enzyme, respectively. Optimal temperature was 5 °C higher for immobilized enzyme than that of the free enzyme. Thermal and storage stabilities were found to be increased upon immobilization. Finally, the immobilized lipase was used for the production of green apple flavor (i.e., ethyl valerate) in hexane medium. © 2010 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Öztürk, Temel | Göktaş, Melahat | Savaş, Bedrettin | Işıklar, Mustafa | Atalar, Mehmet Nuri | Hazer, Baki

Article | 2014 | E-Polymers14 ( 1 ) , pp.27 - 34

Synthesis of poly(vinyl chloride-graft-2-vinylpyridine) graft copolymers was carried out by reversible addition-fragmentation chain transfer (RAFT) polymerization of 2-vinylpyridine using a novel macroinitiator (RAFT macroinitiator). For this purpose, RAFT macroinitiator was obtained from the potassium salt of ethyl xanthogenate and poly(vinyl chloride) (PVC). Then the graft copolymers were synthesized by using RAFT macroinitiator and 2-vinylpyridine. The principal parameters such as monomer concentration, initiator concentration, and polymerization time that affect the polymerization reaction were studied. The effect of the reactio . . .n conditions on the heterogeneity index and molecular weight was also investigated. The block lengths of the graft copolymers were calculated by using 1H nuclear magnetic resonance (1H NMR) spectra. The block lengths of the copolymers could be adjusted by varying the monomer and initiator concentrations. The characterizations of the samples were carried out by using 1H NMR, Fourier-transform infrared spectroscopy, gel-permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, and fractional precipitation (? value) techniques. RAFT polymerization is used to control the polymerization of 2-vinylpyridine over a broad range of molecular weights Daha fazlası Daha az

Köroğlu, Ayşegül | Şahin, Onur | Kürkçüoğlu, Işın | Dede, Doğu Ömür | Özdemir, Tonguç | Hazer, Baki

Article | 2016 | Journal of Applied Oral Science24 ( 6 ) , pp.590 - 596

Objective: The aim of the present study was to evaluate the mechanical and thermal characteristics of two denture base acrylic resins containing silver nanoparticles (AgNPs). Material and Methods: Two different acrylic denture base resins (heat-polymerized and microwave polymerized) containing 0.3, 0.8 and 1.6 wt% AgNPs were evaluated for flexural strength, elastic modulus and impact strength. The glass transition temperature (Tg) and relative heat capacity (Cp) of the samples were determined from the Differential Scanning Calorimetry (DSC) results. For statistical analysis, two-way ANOVA and Tukey-HSD tests were performed. Results: . . . Addition of 0.8% and 1.6% AgNPs in microwave-polymerized resin significantly decreased the transverse strength and elastic modulus. In terms of impact strength, the addition of AgNPs has no effect on both resin groups. Glass transition temperature (Tg) was decreased with the addition of AgNPs for both denture base resins. Conclusions: The incorporation of AgNPs, generally used for antimicrobial efficiency, affected the transverse strength of the denture base acrylic resins depending on the concentration of nanoparticles. Tg was decreased with the addition of AgNPs for both denture base resins. © 2016, Faculdade de Odontologia de Bauru. All rights reserved Daha fazlası Daha az

Kılıçay, Ebru | Erdal, Ebru | Hazer, Baki | Türk, Mustafa | Denkbaş, Emir Baki

Article | 2016 | Artificial Cells, Nanomedicine and Biotechnology44 ( 8 ) , pp.1938 - 1948

Amphiphilic poly(3-hydroxylalkanoate) (PHA) copolymers find interesting applications in drug delivery. The aim of this study was to prepare nucleic acid adsorbed on (PHB-b-PEG-NH2) nanoparticle platform for gene delivery. For this purpose, PHB-b-PEG-NH2 block copolymers were synthesized via transesterification reactions. The copolymers obtained were characterized by Proton Nuclear Magnetic Resonance (1H-NMR), Fourier Transform Infrared Spectrometer (FTIR), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) techniques. The cytotoxic, apoptotic and necrotic effects of these nanoparticles in the MDA 231 human . . .breast cancer cell, the A549 human lung cancer cell and the L929 fibroblast cell lines were also investigated. © 2015 Taylor & Francis Daha fazlası Daha az

Öztürk, Temel | Göktaş, Melahat | Hazer, Baki

Article | 2010 | Journal of Applied Polymer Science117 ( 3 ) , pp.1638 - 1645

One-step synthesis of star copolymers by reversible addition-fragmentation chain transfer (RAFT) and ring-opening polymerization (ROP) by using a novel dual initiator is reported. Triarm block copolymers comprising one polystyrene (or polyacrylamide) arm and two poly(b-butyrolactone) arms were synthesized in one-step by simultaneous RAFT polymerization of styrene (St) (or acrylamide, designated as AAm) and ROP of b-butyrolactone (BL) in the presence of a novel trifunctional initiator, 1,2-propanediol ethyl xanthogenate (RAFT-ROP agent). This dual initiator was obtained through the reaction of 3-chloro-1,2- propanediol with the potas . . .sium salt of ethyl xanthogenate. The principal parameters such as monomer concentration, initiator concentration, and polymerization time that affect the one-step polymerization reaction were evaluated. The characterization of the products was achieved using Fourier-transform infrared spectroscopy (FTIR), 1H-nuclear magnetic resonance (1HNMR),13C-nuclear magnetic resonance ( 13C-NMR), Gas chromatography-mass spectrometry (GC-MS), gel-permeation chromatography (GPC), thermogravimetric analysis (TGA), and fractional precipitation (c) techniques. VC 2010 Wiley Periodicals, Inc Daha fazlası Daha az

Allı, Abdulkadir | Hazer, Baki

Article | 2009 | Hacettepe Journal of Biology and Chemistry37 ( 1 ) , pp.23 - 31

A new macromonomer initiator for atom transfer radical polymerization (ATRP-MIM) based on polyethylene glycol (Mn= 660 Da) (PEG) was synthesized by the reaction of hydroxyl end of the mono-methacryloyl polyethylene glycol with 2-bromopropanoyl chloride leading to methacryloyl polyethylene glycol 2-bromopropanoyl ester (v-PEG-Br). Poly(ethylene glycol) functionalized with methacrylate at one end was reacted with 2-bromopropionyl chloride to form a macromonomeric initiator for ATRP. Self condensing ATRP-MIM polymerization yielded branched PEG with low cross-linked fraction (3-29 wt%). In the same polymerization condition, self condens . . .ing ATRP-MIM polymerization was found faster than that of conventional free radical macromonomer initiators which behave as macro crosslinker, macro initiator and macromonomer. Besides the PEG obtained has still unreacted double bonds and halides leading to the further branching. In the second step, ATRP of methyl methacrylate was initiated by the MIM-ATRP using the copper coordination complex CuBr / N,N,N’,N’,N’’-pentamethyl diethylenetriamine (PMDETA). The ATRP-MIM and the chloroform soluble branched polymers obtained were characterized by 1H NMR spectroscopy and gel permeation chromatography (GPC). Variation of gel polymer content, molecular weight of the soluble parts and conversion of the monomers with the changing polymerization conditions were also discussed. A new macromonomer initiator for atom transfer radical polymerization (ATRP-MIM) based on polyethylene glycol (Mn= 660 Da) (PEG) was synthesized by the reaction of hydroxyl end of the mono-methacryloyl polyethylene glycol with 2-bromopropanoyl chloride leading to methacryloyl polyethylene glycol 2-bromopropanoyl ester (v-PEG-Br). Poly(ethylene glycol) functionalized with methacrylate at one end was reacted with 2-bromopropionyl chloride to form a macromonomeric initiator for ATRP. Self condensing ATRP-MIM polymerization yielded branched PEG with low cross-linked fraction (3-29 wt%). In the same polymerization condition, self condensing ATRP-MIM polymerization was found faster than that of conventional free radical macromonomer initiators which behave as macro crosslinker, macro initiator and macromonomer. Besides the PEG obtained has still unreacted double bonds and halides leading to the further branching. In the second step, ATRP of methyl methacrylate was initiated by the MIM-ATRP using the copper coordination complex CuBr / N,N,N’,N’,N’’-pentamethyl diethylenetriamine (PMDETA). The ATRP-MIM and the chloroform soluble branched polymers obtained were characterized by 1H NMR spectroscopy and gel permeation chromatography (GPC). Variation of gel polymer content, molecular weight of the soluble parts and conversion of the monomers with the changing polymerization conditions were also discussed Daha fazlası Daha az

Hazer, Baki | Kalaycı, Özlem Alunordu

Proceedings | 2014 | ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY247 , pp.23 - 31

247th National Spring Meeting of the American-Chemical-Society (ACS) -- MAR 16-20, 2014 -- Dallas, TX WOS: 000348457604271