Bulunan: 8 Adet 0.002 sn
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One-step synthesis of block-graft copolymers via simultaneous reversible-addition fragmentation chain transfer and ring-opening polymerization using a novel macroinitiator

Öztürk, Temel | Atalar, Mehmet Nuri | Göktaş, Melahat | Hazer, Baki

Article | 2013 | Journal of Polymer Science, Part A: Polymer Chemistry51 ( 12 ) , pp.2651 - 2659

One-step synthesis of block-graft copolymers by reversible addition-fragmentation chain transfer (RAFT) and ring-opening polymerization (ROP) by using a novel initiator was reported. Block-graft copolymers were synthesized in one-step by simultaneous RAFT polymerization of n-butylmethacrylate (nBMA) and ROP of ?-caprolacton (CL) in the presence of a novel macroinitiator (RAFT-ROP agent). For this purpose, first epichlorohydrin (EPCH) was polymerized by using H2SO4 via cationic ring-opening mechanism. And then a novel RAFT-ROP agent was synthesized by the reaction of potassium ethyl xanthogenate and polyepichlorohydrin (poly-EPCH). B . . .y using the RAFT-ROP agent, poly[CL-b-EPCH-b-CL-(g-nBMA)] block-graft copolymers were synthesized. The principal parameters such as monomer concentration, initiator concentration, and polymerization time that affect the one-step polymerization reaction were evaluated. The block lengths of the block-graft copolymers were calculated by using 1H-nuclear magnetic resonance (1H NMR) spectrum. The block length could be adjusted by varying the monomer and initiator concentrations. The characterization of the products was achieved using 1H NMR, Fourier-transform infrared spectroscopy, gel-permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, elemental analysis, and fractional precipitation (?) techniques. © 2013 Wiley Periodicals, Inc Daha fazlası Daha az

Novel water soluble Soya oil polymer from oxidized Soya oil polymer and diethanol amine

Acar, Merve | Çoban, Selim | Hazer, Baki

Article | 2013 | Journal of Macromolecular Science, Part A: Pure and Applied Chemistry50 ( 3 ) , pp.287 - 296

A cold water soluble, biobased polymer derived from autoxidized soya oil has been described. Oxidized soya oil polymer was obtained by exposure to air under daylight at room temperature. The thickness of the soya oil at the beginning of the reaction and the oxidation time adversely influenced the molecular weight of the soya oil polymer obtained. The oxidized soya oil polymer obtained was then reacted with diethanol amine to obtain a hydroxylated soya oil polymer. The cold water soluble hydroxylated soya oil polymer was characterized by viscosity measurements, elemental analysis, FT-IR, 1H-NMR, 13C-NMR and cosy-NMR. © 2013 Copyright . . . Taylor and Francis Group, LLC Daha fazlası Daha az

Optical characterization of CdS nanoparticles embedded into the comb-type amphiphilic graft copolymer

Kalaycı, Özlem A. | Duygulu, Özgür | Hazer, Baki

Article | 2013 | Journal of Nanoparticle Research15 ( 1 ) , pp.287 - 296

This study refers to the synthesis and characterization of a novel organic/inorganic hybrid nanocomposite material containing cadmium sulfide (CdS) nanoparticles. For this purpose, a series of polypropylene (PP)-g-polyethylene glycol (PEG), PP-g-PEG comb-type amphiphilic graft copolymers were synthesized. PEGs with Mn = 400, 2000, 3350, and 8000 Da were used and the graft copolymers obtained were coded as PPEG400, PPEG2000, PPEG3350, and PPEG8000. CdS nanoparticles were formed in tetrahydrofuran solution of PP-g-PEG amphiphilic comb-type copolymer by the reaction between aqueous solutions of Na2S and Cd(CH3COO)2 simultaneously. Mice . . .lle formation of PPEG2000 comb-type amphiphilic graft copolymer in both solvent/non-solvent (petroleum ether-THF) by transmission electron microscopy (TEM). The optical characteristics, size morphology, phase analysis, and dispersion of CdS nanoparticles embedded in PPEG400, PPEG2000, PPEG3350, and PPEG8000 comb-type amphiphilic graft copolymer micelles were determined by high resolution TEM (HRTEM), energy dispersive spectroscopy, UV-vis spectroscopy, and fluorescence emission spectroscopy techniques. The aggregate size of PPEG2000-CdS is between 10 and 50 nm; however, in the case of PPEG400-CdS, PPEG3350-CdS, and PPEG8000-CdS samples, it is up to approximately 100 nm. The size of CdS quantum dots in the aggregates for PPEG2000 and PPEG8000 samples was observed as 5 nm by HRTEM analysis, and this result was also supported by UV-vis absorbance spectra and fluorescence emission spectra. © 2012 Springer Science+Business Media Dordrecht Daha fazlası Daha az

Osteogenic activities of polymeric soybean oil-g-polystyrene membranes

Tığlı-Aydın, Rahime Seda | Hazer, Baki | Acar, Merve | Gümüşderelioğlu, Menemşe

Article | 2013 | Polymer Bulletin70 ( 7 ) , pp.2065 - 2082

A novel biocompatible copolymer membrane was synthesized and characterized for use in guided bone regeneration using polymeric soybean oil-g-polystyrene (PSO-g-PS) graft copolymer which was successfully obtained by free radical polymerization of styrene initiated by PSO peroxide as a macroinitiator at 80 C. Osteoblastic cellular activities of MC3T3-E1 cells on PSO-g-PS membranes with different soybean oil composition (PSO-g-PS1, PSO-g-PS2, and PSO-g-PS3) were evaluated. Nuclear magnetic resonance (1H NMR) spectra showed that PSO inclusion (mol%) was found to be 27, 69, and 51 % for PSO-g-PS1, PSO-g-PS2, and PSO-g-PS3 membranes, resp . . .ectively. Superior biocompatibility of the PSO-g-PS membranes was determined compared to polystyrene tissue culture plates (TCPS) as positive control. Cell proliferation was enhanced on PSO-g-PS2 and PSO-g-PS3 membranes compared to PSO-g-PS1 membranes (p < 0.001), and a statistically significant higher ALP value of MC3T3-E1 cells on PSO-g-PS2 membranes (p < 0.05) suggested that proliferation and differentiation of preosteoblastic on PSO-g-PS membranes were enhanced with regard to soybean oil content within the membranes. Thus, the present study suggests that PSO-g-PS2 membranes, which showed a favorable biological environment for the preosteoblastic cells, can be well suited for bone tissue engineering applications. © 2013 Springer-Verlag Berlin Heidelberg Daha fazlası Daha az

Synthesis of antibacterial amphiphilic elastomer based on polystyrene-block-polyisoprene-block-polystyrene via thiol-ene addition

Keleş, Elif | Hazer, Baki | Cömert, Füsun B.

Article | 2013 | Materials Science and Engineering C33 ( 3 ) , pp.1061 - 1066

A new type of amphiphilic antibacterial elastomer has been described. Thermoplastic elastomer, polystyrene-block-polyisoprene-block-polystyrene (PS-b-PI-b-PS) triblock copolymer was functionalized in toluene solution by free radical mercaptan addition in order to obtain an amphiphilic antibacterial elastomer. Thiol terminated PEG was grafted through the double bonds of PS-b-PI-b-PS via free radical thiol-ene coupling reaction. The antibacterial properties of the amphiphilic graft copolymers were observed. The original and the modified polymers were used to create microfibers in an electro-spinning process. Topology of the electrospu . . .n micro/nanofibers were studied by using scanning electron microscopy (SEM). The chemical structures of the amphiphilic comb type graft copolymers were elucidated by the combination of elemental analysis, 1H NMR, 13C NMR, GPC and FTIR. © 2012 Elsevier B.V. All Rights Reserved Daha fazlası Daha az

Solid-phase extraction of lead and copper on a polyhydroxybutyrate-b-polydimethyl siloxane (PHB-b-PDMS) block copolymer disc and flame atomic absorption spectrometric determination of them in water and food samples

Tüzen, Mustafa | Ünsal, Yunus Emre | Soylak, Mustafa | Akkırman, Zeynep | Hazer, Baki

Article | 2013 | International Journal of Food Science and Technology48 ( 11 ) , pp.2384 - 2390

A separation and preconcentration procedure based on solid-phase extraction of Cu(II) and Pb(II) as their Sudan III chelates on polyhydroxybutyrate-b-polydimethyl siloxane (PHB-b-PDMS) block copolymer disc has been established. Various analytical parameters including pH, amount of Sudan III, eluent type and volume, sample volume, flow rates were optimised. The effects of concomitant ions on the retentions of the analyte ions on PHB-b-PDMS disc were also examined. The detection limits for Cu(II) and Pb(II) were found to be 2.3 and 4.9 µgL-1, respectively. Preconcentration factor was found to be sixty. Relative standard deviation was . . .found to be 5%. The accuracy of the method was confirmed by analysing certified reference materials (TMDA 54.4 fortified lake water and NIST 1515 Apple leaves). Optimised method was applied to determine the analyte ions in various water and food samples from Turkey. © 2013 Institute of Food Science and Technology Daha fazlası Daha az

In vivo application of poly-3-hydroxyoctanoate as peripheral nerve graft

Hazer, Derya Burcu | Bal, Ercan | Nurlu, Gülay | Benli, Kemal | Balcı, Serdar | Öztürk, Feral | Hazer, Baki

Article | 2013 | Journal of Zhejiang University: Science B14 ( 11 ) , pp.993 - 1003

Objective: This study aims to investigate the degree of biocompatibility and neuroregeneration of a polymer tube, poly-3-hydroxyoctanoate (PHO) in nerve gap repair. Methods: Forty Wistar Albino male rats were randomized into two groups: autologous nerve gap repair group and PHO tube repair group. In each group, a 10-mm right sciatic nerve defect was created and reconstructed accordingly. Neuroregeneration was studied by sciatic function index (SFI), electromyography, and immunohistochemical studies on Days 7, 21, 45 and 60 of implantation. Biocompatibility was analyzed by the capsule formation around the conduit. Biodegradation was . . .analyzed by the molecular weight loss in vivo. Results: Electrophysiological and histomorphometric assessments demonstrated neuroregeneration in both groups over time. In the experimental group, a straight alignment of the Schwann cells parallel to the axons was detected. However, autologous nerve graft seems to have a superior neuroregeneration compared to PHO grafts. Minor biodegradation was observed in PHO conduit at the end of 60 d. Conclusions: Although neuroregeneration is detected in PHO grafts with minor degradation in 60 d, autologous nerve graft is found to be superior in axonal regeneration compared to PHO nerve tube grafts. PHO conduits were found to create minor inflammatory reaction in vivo, resulting in good soft tissue response. © 2013 Zhejiang University and Springer-Verlag Berlin Heidelberg Daha fazlası Daha az

DNA adsorption and dynamic mechanical analysis of polymeric oil/oil acid copolymers

Çakmaklı, Birten | Hazer, Baki | Erdoğan, Taner | Mutlu, Ayşe Gül

Article | 2013 | Journal of Polymer Research20 ( 3 ) , pp.993 - 1003

A variety of new polymeric materials [Polylinseed oil-g-PMMA (PLO-g-PMMA), Polylinseed oil-g-PS (PLO-g-PS), Polysoybean oil-g-PMMA (PSB-g-PMMA), Polylinoleic acid-g-PMMA (PLina-g-PMMA), Polylinoleic acid-g-PS (PLina-g-PS), Polylinoleic acid-g-PnBMA (PLina-g-PnBMA), Polyhydroxy alkanoate-sy-g- Polysoybean oil-g-PMMA (PHA-PSB-PMMA) and Polyhydroxy alkanoate-sy-g- Polylinoleic acid-g-PMMA (PHA-PLina-PMMA)] were prepared from soluble polymeric oil/oily acid peroxides initiating the co-polymerization of Poly(methyl methacrylate) (PMMA), Polystyrene (PS) and Poly(n-butyl methacrylate) (PnBMA). Pure PMMA, PS, PnBMA and these copolymers con . . .tain different polymeric oil/oil acid initiators were investigated as to the relationship between their dynamic mechanical properties. The DMA results show that the transition from glassy to rubbery behavior is broad for these polymers due to the presence of the triglyceride/oil acid molecules acting like plasticizers in the system. Furthermore, they were compared with dynamic mechanical analysis (DMA) and differential scanning calorimeter (DSC) analysis results. The mechanical properties of these homopolymer and copolymers were also assessed by tensile tests of the polymers in terms of the stress and strain values at the break point. When these results were compared with those for PMMA and PnBMA, it is worth noting that copolymer samples containing PLO, PSB, or PLina in its structure showed changed stress at their break point or in the strain value at its break point. The contact angle testing and DNA adsorption of oil/oil acid copolymers were also studied. Compared with homopolymers, the hydrophilicity and DNA adsorption of the copolymer samples improved because of the presence of PLO, PSB, or PLina blocks. Considering all these results, it is recommended that the copolymers used as candidate biomaterials. © 2013 Springer Science+Business Media Dordrecht Daha fazlası Daha az

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