Bulunan: 19 Adet 0.001 sn
Koleksiyon [19]
Tam Metin [2]
Yayın Türü [1]
Yazar [20]
Konu Başlıkları [20]
Yayıncı [13]
Yayın Dili [1]
Dergi Adı [19]
Nitroxide-mediated copolymerization of styrene and pentafluorostyrene initiated by polymeric linoleic acid

Allı, Abdulkadir | Allı, Sema | Becer, C. Remzi | Hazer, Baki

Article | 2016 | European Journal of Lipid Science and Technology118 ( 2 ) , pp.279 - 287

Polymeric linoleic asit graft copolymers were synthesized via a nitroxide-mediated radical polymerization (NMRP) method in the presence of 2,2-6,6-tetramethylpiperidinyl-1-oxy (TEMPO). For this purpose, PLina-ox was exposed to polymerization with styrene (Sty) or Sty and pentafluorostyrene (F5Sty) in the presence of TEMPO by NMRP method in order to obtain PLina-g-PSty and PLina-g-PF5Sty-g-PSty graft copolymers with controlled structure and low polydispersity. Chain extension study was evaluated. Principal parameters, such as monomer concentration, initiator concentration, and polymerization time, which effect the polymerization reac . . .tions, were evaluated. The products thus obtained were well characterized by 1H NMR, GPC, and 19F NMR measurements. Practical application: We report for the first time the synthesis of PLina-g-PSty and PLina-g-PSty-g-PF5Sty graft copolymers in the presence of TEMPO. NMRP reactions were performed in the presence of TEMPO in order to obtain graft copolymers with controlled molecular weight and polydispersity. Chain-extension reactions were also successfully carried out because of the activation of TEMPO terminated chain ends of graft copolymers. Pure linoleic acid was auto-oxidized under daylight and air oxygen, yielding peroxidized PLina (PLina-ox). PLina-ox has been used in the polymerization of styrene (Sty) or copolymerization of Sty and pentafluorostyrene (F5Sty). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Daha fazlası Daha az

Novel graphene-modified poly(styrene-b-isoprene-b-styrene) enzymatic fuel cell with operation in plant leaves

Korkut, Şeyda | Kılıç, Muhammet Samet | Uzunçar, Sinan | Hazer, Baki

Article | 2016 | Analytical Letters49 ( 14 ) , pp.2322 - 2336

A carboxylated poly(styrene-b-isoprene-b-styrene) triblock copolymer was synthesized for the construction of an enzymatic fuel cell. Glucose oxidase and bilirubin oxidase were chemically immobilized via the carboxylated functional groups of the polymer. The enzymatic fuel cell working electrodes were modified with graphene to accelerate the electron transfer rate of the system. Essential design and operational parameters were carefully optimized for improving the power of the enzymatic fuel cell. A power density of 20 µW cm-2 with only 4 µg of immobilized bilirubin oxidase was generated from 30 mM glucose at 0.72 V. The improved enz . . .ymatic fuel cell was tested in a plant leaf. A power density of 14 nW cm-2 was generated with glucose produced by photosynthesis reactions conducted during 30 min in the leaf. © 2016, Taylor & Francis Group, LLC Daha fazlası Daha az

The synthesis and characterization of novel quinone-amine polymers from the reactions of 2,3-dichloro-1,4-naphthoquinone and polyoxypropylenediamines

Ayla-Şahinler, Ayla | Bahar, Hakan | Yavuz, Şenol | Hazer, Baki | İbiş, Cemil

Article | 2016 | Phosphorus, Sulfur and Silicon and the Related Elements191 ( 3 ) , pp.438 - 443

A series of novel N-and N,N'-bis(quinonyl)amines were synthesized from the reactions of 2,3-dichloro-1,4-naphthoquinone (1) and polyoxypropylenediamines. The novel quinone-amine polymers were treated with some thiols in next step and N,S-substituted compounds were obtained. The structures of the novel products were characterized by micro-analysis, 1H NMR, UV-VIS, 13C NMR, and MS. The electrochemical properties of some of the novel amine-quinone polymers derivatives were also investigated by cyclic voltammetry. The number of molecular weight (Mn) of polymer compounds was also determined by Gel Permeation Chromatography (GPC). © 2016 . . .Taylor & Francis Group, LLC Daha fazlası Daha az

Synthesis and characterization of graft copolymers based on polyepichlorohydrin via reversible addition-fragmentation chain transfer polymerization

Öztürk, Temel | Kayğın, Oğuz | Göktaş, Melahat | Hazer, Baki

Article | 2016 | Journal of Macromolecular Science, Part A: Pure and Applied Chemistry53 ( 6 ) , pp.362 - 367

In this study, synthesis of poly(epichlorohydrin-g-methyl methacrylate) graft copolymers by reversible addition-fragmentation chain transfer (RAFT) polymerization was reported. For this purpose, epichlorohydrin was polymerized by using HNO3 via cationic ring-opening mechanism. A RAFT macroinitiator (macro-RAFT agent) was obtained by the reaction of potassium ethyl xanthogenate and polyepichlorohydrin. The graft copolymers were synthesized using macro-RAFT agent as initiator and methyl methacrylate as monomer. The synthesis of graft copolymers was conducted by changing the time of polymerization and the amount of monomer-initiator co . . .ncentration that affect the RAFT polymerization. The effects of these parameters on polymerization were evaluated via various analyses. The characterization of the products was determined using 1H-nuclear magnetic resonance (1H-NMR), Fourier-transform infrared spectroscopy, gel-permeation chromatography, thermogravimetric analysis, elemental analysis, and fractional precipitation techniques. The block lengths of the graft copolymers were calculated by using 1H-NMR spectrum. It was observed that the block length could be altered by varying the monomer and initiator concentrations. © 2016 Taylor & Francis Group, LLC Daha fazlası Daha az

Antimicrobial effect of polymer-based silver nanoparticle coated pedicle screws: Experimental research on biofilm inhibition in Rabbits

Hazer, Derya Burcu | Sakar, Mustafa | Dere, Yelda | Altınkanat, Gülşen | Ziyal, M. İbrahim | Hazer, Baki

Article | 2016 | Spine41 ( 6 ) , pp.362 - 367

Study Design. Antimicrobial effect of a novel silverimpregnated pedicle screw in rabbits. Objective. A novel spine implant model was designed to study the antimicrobial effect of a modified Titanium (Ti) pedicle screws with methicillin-resistant Staphylococcus aureus (MRSA) in multiple surgical sites in the lumbar spine of a rabbit. Summary of Background Data. Infection in spinal implant is of great concern. Anti-infection strategies must be tested in relevant animal models that will lead to appropriate clinical studies. Methods. Fourteen New Zealand white rabbits were divided into 2 groups: group 1: infected unmodified Ti screw gro . . .up (n=6), and group 2: infected polyethylene glycol grafted, polypropylene-based silver nanoparticle (PP-g-PEG-Ag) covered Ti screw group (n=6), and 2 rabbits as sterile (sham-operated and control) group. In all groups, left L4-right L6 vertebra levels were exposed and screws were drilled to transverse processes after contamination of burr holes and surrounding tissue with 0.1mL of 106 colony forming units (CFU) MRSA solutions in groups 1 and 2. After 21 days, samples were collected and infection was analyzed via light and scanning electron microscopy and culturing. Silver nanoparticles (Ag-NP) on the screws and tissues were assayed pre and postoperatively. Results. The bacterial colony count for modified-Ti screw group was lower than for unmodified Ti screw (17.2 versus 200 x 103 CFU/mL, P=0.029) with less biofilm formation. There was no difference in duration of surgery among groups and within the surgical sites. Ag-NPs were detected on the screw surface postoperatively. Conclusion. This novel experimental design of implantation in rabbits is easy to apply and resembles human stabilization technique. Modified Ti screws were shown to have antimicrobial effect especially inhibiting the biofilm formation. This anchored Ag NPs that remained after 21st day of implantation shows that it is resistant to tapping forces of the screw. © 2016 Wolters Kluwer Health, Inc. All rights reserved Daha fazlası Daha az

One-step synthesis of triarm block copolymers by simultaneous atom transfer radical and ring-opening polymerization

Öztürk, Temel | Yavuz, Mahmut | Göktaş, Melahat | Hazer, Baki

Article | 2016 | Polymer Bulletin73 ( 6 ) , pp.1497 - 1513

One-step synthesis of poly(MMA-b-CL) triarm block copolymers was carried out by atom transfer radical polymerization of methyl methacrylate (MMA) and ring-opening polymerization of ?-caprolactone (CL) using 3-chloro-1,2-propanediol trifunctional initiator. The triarm block copolymers comprising one poly-MMA arm and two poly-CL arms were synthesized by changing some polymerization conditions such as monomer/initiator concentration, polymerization time. The effect of the reactions conditions on the polydispersity and molecular weights was also investigated. The block lengths of the block copolymers were calculated by using 1H-nuclear . . .magnetic resonance (1H-NMR) spectrum. It was observed that the block length could be altered by varying the monomer and initiator concentrations. The characterization of the products was achieved by using 1H-NMR, Fourier-transform infrared spectroscopy, gel-permeation chromatography, differential scanning calorimetry, thermogravimetric analysis and fractional precipitation techniques. © 2015, Springer-Verlag Berlin Heidelberg Daha fazlası Daha az

Electrochemical, continuous-flow determination of p-benzoquinone on a gold nanoparticles poly(propylene-co-imidazole) modified gold electrode

Korkut, Şeyda | Uzunçar, Sinan | Kılıç, Muhammet Samet | Hazer, Baki

Article | 2016 | Instrumentation Science and Technology44 ( 6 ) , pp.614 - 628

A novel continuous flow biosensor based on gold nanoparticles and poly(propylene-co-imidazole) was developed for the online determination of p-benzoquinone. The amperometric response was measured as a function of p-benzoquinone concentration at an applied potential of -50 mV. The hydrogen peroxide concentration was optimized and fixed at 1 mM in samples. The mass transfer resistance of the copolymer film was minimized, and the flow cell was regenerated quickly at 1 mL/min. The resulting device provided good analytical performance based on a linear dynamic range from 5–100 µM, a short response time of 3 s, a detection limit of 3.3 µM . . ., excellent repeatability with a relative standard deviation of 0.82%, long-term stability of 95% after four weeks, and an accuracy of 105%. The gold nanoparticles enhanced the electron transfer rate on the electrode. The apparent Michaelis-Menten constant was 4 mM, showing that the enzyme retained catalytic specificity and provided high activity for p-benzoquinone. © 2016, Taylor & Francis Daha fazlası Daha az

Silver nanoparticle incorporation effect on mechanical and ther at properties of denture base acrylic resins

Köroğlu, Ayşegül | Şahin, Onur | Kürkçüoğlu, Işın | Dede, Doğu Ömür | Özdemir, Tonguc | 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 Daha fazlası Daha az

Synthesis and characterization of novel rod-coil (tadpole) poly(linoleic acid) based graft copolymers

İnce, Özge | Akyol, Elvan | Sulu, Elvan | Şanal, Timur | Hazer, Baki

Article | 2016 | Journal of Polymer Research23 ( 1 ) , pp.1 - 10

Synthesis of novel poly (styrene)-g-poly(linoleic acid)-g-poly(ethylene glycol) amphiphilic rod-coil tadpole and poly (styrene)-g-poly(linoleic acid)-g-poly (dimethyl siloxane) double hydrophobic rod-coil tadpole graft copolymers have been reported. In the first step, poly(linoleic acid) peroxide macro initiator (PLina) was prepared by exposing linoleic acid to air at room temperature for three weeks, in view of the autoxidation process. In the second step, poly styrene-g-poly linoleic acid graft copolymer (PLinaS) was prepared by the polymerization of styrene initiated by PLina. In the third step, PS-g-PLina-g-PEG rod-coil tadpole . . .amphiphilic graft copolymer and PS-g-PLina-g-PolyPDMS rod-coil tadpole double hydrophobic graft copolymers were obtained by the reaction of carboxylic ends of PLinaS with polyethylene glycol (PEG) with primary amine terminal and poly (dimethyl siloxane) (PDMS) with primary amine terminals. The target copolymers and all intermediates were well characterized by GPC, FTIR, 1H NMR, DSC, and TGA in detail. © 2015, Springer Science+Business Media Dordrecht Daha fazlası Daha az

Solid phase extraction of uranium on a new brush type graft copolymer and spectrophotometric determination of its in water samples

Tüzen, Mustafa | Esra, Bağda | Hazer, Baki

Article | 2016 | Journal of Radioanalytical and Nuclear Chemistry310 ( 3 ) , pp.1255 - 1263

A new versatile solid phase extraction and spectrophotometric determination of uranium (VI) was proposed with using poly(caprolactone-b-vinyl benzyl chloride-g-dimethyl amino ethyl methacrylate), poly(CL-b-VB-g-DMAEMA), amphiphilic brush type block/graft copolymer. The method is based on the adsorption of uranium(VI)-pyrocatechol violet complex on surface on the adsorbent. The parameters such as pH, amount of ligand and copolymer, sample volume were optimized. Detection limit, preconcentration factor and relative standard deviation were found as 0.45 µg L-1, 100 and 3.8 %, respectively. Adsorption capacity of the polymer for uranium . . .(VI) was found 52 mg g-1. The method was applied to different water samples and standard reference materials. © 2016, Akadémiai Kiadó, Budapest, Hungary Daha fazlası Daha az

Solution electrospinning of polypropylene-based fibers and their application in catalysis

Berber, Emine | Horzum, Nesrin | Hazer, Baki | Demir, Mustafa M.

Article | 2016 | Fibers and Polymers17 ( 5 ) , pp.760 - 768

Since the dissolution of polyolefins is a chronic problem, melt processing has been tacitly accepted as an obligation. In this work, polypropylene (PP) was modified on molecular level incorporating poly(ethylene glycol) (PEG) as graft segment (PP-g-PEG) in a range of 6 to 9 mol%. Gold nanoparticles were nucleated in the presence of the copolymer chains via redox reaction. The dissolution of the amphiphilic comb-type graft copolymers containing gold nanoparticles (80 nm in diameter) was achieved in toluene and successfully electrospun from its solution. The diameter of composite fibers was in the range from 0.3 to 2.5 µm. The design . . .of the structurally organized copolymer fiber mats provided a support medium for the nanoparticles enhancing the active surface area for the catalytic applications. The resulting composite fibers exhibited rapid catalytic reduction of methylene blue (MB) dye in the presence of sodium borohydride (NaBH4) compared to corresponding composite cast film. © 2016, The Korean Fiber Society and Springer Science+Business Media Dordrecht Daha fazlası Daha az

Solid phase extraction of lead, cadmium and zinc on biodegradable polyhydroxybutyrate diethanol amine (PHB-DEA) polymer and their determination in water and food samples

Tüzen, Mustafa | Şahiner, Samet | Hazer, Baki

Article | 2016 | Food Chemistry210 , pp.115 - 120

A new biodegradable polyhydroxybutyrate diethanol amine (PHB-DEA) polymer was used as adsorbent for the sensitive and selective separation, preconcentration and determination of Pb(II), Cd(II) and Zn(II) by using atomic absorption spectrometry. Diethyl dithiocarbamate was used as chelating reagent. Analytical parameters such as pH, eluent type and its volume, flow rates of sample solution, ligand amount, sample volume were optimized. Effects of some cations, anions and transition metal ions were also investigated. Enrichment factor and relative standard deviation were found to be 100 and 3%, respectively. The limits of detection bas . . .ed on three times standard deviation of blanks (N = 21) were found 1.05 µg L-1 for Pb(II), 0.42 µg L-1 for Cd(II) and 0.13 µg L-1 for Zn(II). Limits of quantification (10 s, N = 21) were found 3.47 µg L-1 for Pb(II), 1.39 µg L-1 for Cd(II) and 0.43 µg L-1 for Zn(II). Accuracy evaluation of the method was confirmed with analyses of certified reference materials (NIST SRM 1515 Apple leaves, IAEA 336 Lichen, GBW 07605 Tea). Optimized method was applied to tap water and food samples after microwave digestion method. Cadmium and lead values in some samples were found higher than legal limits. © 2016 Elsevier Ltd. All rights reserved Daha fazlası Daha az

6698 sayılı Kişisel Verilerin Korunması Kanunu kapsamında yükümlülüklerimiz ve çerez politikamız hakkında bilgi sahibi olmak için alttaki bağlantıyı kullanabilirsiniz.

Bu site altında yer alan tüm kaynaklar Creative Commons Alıntı-GayriTicari-Türetilemez 4.0 Uluslararası Lisansı ile lisanslanmıştır.