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Bulunan: 165 Adet 0.001 sn
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Filtreler
Filtreler
Bulunan: 165 Adet 0.001 sn
Koleksiyon [20]
Tam Metin [2]
Yayın Türü [7]
Yazar [20]
Yayın Yılı [20]
Konu Başlıkları [20]
Yayıncı [20]
Yayın Dili [2]
Dergi Adı [20]
Dispersion polymerization of styrene and methyl methacrylate initiated by macromonomeric azoinitiator

Yıldız, Ufuk | Hazer, Baki

Article | 1999 | Angewandte Makromolekulare Chemie265 , pp.16 - 19

The free radical dispersion polymerization of styrene (St) and methyl methacrylate (MMA) initiated by poly(oxyethylene) (PEO) macroazoinimer (MIM-400) in water/ethanol, was investigated at three different temperatures (50, 60 and 80°C) for seven polymerization times (3, 6, 9, 12, 24, 36 and 48 h). PSt-PEO and PMMA-PEO networks were obtained. In each case, polymer gel fractions depend on the polymerization temperature and polymerization time. With the same initial concentration of MIM-400, maximum gel fraction was found at 80 wt.-% with St copolymerization while 100 wt.-% in case of copolymerization with MMA at 80°C for 48 h. © Wiley . . .-VCH Verlag GmbH, 1999 Daha fazlası Daha az

Synthesis of polytetrahydrofuran macromonomeric peroxy initiators via cationic polymerization

Savaşkan, Sevil | Volga, Cüneyt | Hazer, Baki

Article | 1998 | Designed Monomers and Polymers1 ( 1 ) , pp.111 - 119

Polytetrahydrofuran macromonomeric initiators (poly-THF-inimer) were synthesized via cationic polymerization of THF, initiated by the combination of AgSbFe 6 and mono-, di-, or tetra-bromomethyl benzoyl peroxides, followed by termination with methacrylate anion. The macroinimers were characterized by 1 H-NMR and GPC techniques. Copolymerization of poly-THF-inimers with methyl methacrylate (MMA) gave crosslinked block copolymers. Sol-gel analysis and swelling measurements of the crosslinked product are also reported.

Synthesis of the new cation exchange resins having poly(styrene-caprolactone) units

Yılmaz-Savaşkan, Sevil | Özbayrak, Hulisi | Hazer, Baki

Article | 1997 | TURKISH JOURNAL OF CHEMISTRY21 ( 4 ) , pp.270 - 276

The crosslinked polystyrene-polycaprolactone, PS-PCL-, block copolymers were prepared by the copolymerization of styrene and poly(caprolacton dimethylmethacrylate) (PCL-DM). The molecular weights of polycaprolactone, PCL, PCL-DM were 1250 and 2000. The swelling in H2O or CHCl3 of the sulfonate and unsulfonated block copolymers were determined under comparable conditions and investigated. The capacities of the obtained ion exchange resins were 1.31 and 1.10 meq/g.

Reactions of anionic living polymers with bromomethyl-functionalized benzoyl peroxides

Hazer, Baki | Hirao, Akira | Volga, Cüneyt

Article | 1999 | Macromolecular Chemistry and Physics200 ( 1 ) , pp.71 - 76

In order to synthesize benzoyl peroxide functionalized polystyrene (PSt), polyisoprene (PI) and poly(methyl methacrylate) (PMMA), anionic living PSt, PI, and PMMA were allowed to react with an excess amount of 4-(bromomethyl)benzoyl tert-butyl peroxide (BMtB) or bis[3,5-bis(bromomethyl)benzoyl] peroxide (BDBP) in tetrahydrofuran (THF) at -78°C. The results indicate that coupling reactions leading to dimers are significant during the reaction. Dimer formation was avoided when the living polystyrene was modified to the alcoholate anion by reaction with ethylene oxide (EO). © Wiley-VCH Verlag GmbH, 1999.

Telechelic polyhydroxyalkanoates/polyhydroxybutyrates (PHAs/PHBs)

Allı, Abdulkadir | Hazer, Baki | Adamus, Grażyna | Kowalczuk, Marek

Book Part | 2017 | Handbook of Telechelic Polyesters, Polycarbonates, and Polyethers , pp.65 - 114

Poly(3-hydroxyalkanoate)s, PHAs, are natural polyesters collected as intracellular granules as a result of a metabolic stress upon unbalanced growth, owing to a limited supply of a necessary nutrient and to the presence of an excess of a carbon source [1,2,3,4,5,6,7-8]. PHAs have material properties ranging from rigid and highly crystalline to elastic, rather amorphous, and flexible. Many studies have been reported on the modification reactions of PHAs to enhance their mechanical and thermal properties [9,10,11,12,13,14,15,16-17]. © 2017 by Pan Stanford Publishing Pte. Ltd.

Synthesis and characterization of poly(Ɛ-caprolactone-co-ethylene glycol) star-type amphiphilic copolymers by “click” chemistry and ring-opening polymerization.

Öztürk, Temel | Kılıçlıoğlu, Ali | Savaş, Bedrettin | Hazer, Baki

Article | 2018 | Journal of Macromolecular Science, Part A: Pure and Applied Chemistry55 ( 8 ) , pp.588 - 594

The synthesis of poly(?-caprolactone-co-ethylene glycol) AAB star-type amphiphilic copolymers were carried out by use of a “click” chemistry reaction to block propargyl polyethylene glycol (propargyl-PEG) to terminally azide poly(?-caprolactone) (PCL-N3). For this purpose, propargyl-PEG was synthesized by the reaction of PEGs (3000 Da, 2000 Da, 1500 Da, and 1000 Da) and propargyl chloride. Terminally chloride poly(?-caprolactone) (PCL-Cl) was carried out by means of ring-opening polymerization (ROP) of ?-caprolactone (CL) and 3-chloro-1,2-propanediol. Synthesis of PCL-N3 was obtained by the chemical interaction of PCL-Cl and sodium . . .azide. By reacting propargyl-PEG and PCL-N3, the star-type amphiphilic copolymers were obtained. The characterization of products was accomplished by using multiple instruments including 1H-NMR, FT-IR, GPC, TGA, contact angles, and elemental analysis techniques. © 2018, © 2018 Taylor & Francis Group, LLC Daha fazlası Daha az

Synthesis of microbial elastomers based on soybean oil. Autoxidation kinetics, thermal and mechanical properties

Hazer, Baki | Hazer, Derya Burcu | Çoban, Burak

Article | 2010 | Journal of Polymer Research17 ( 4 ) , pp.567 - 577

Microbial bioelastomers prepared by the autoxidation of the unsaturated medium-long chain length copoly- 3-hydroxyalkanoate's (mlcl-PHAs) based on soybean oily acids (Sy) have been reported. Pseudomonas oleovorans were grown on a series of the mixture of octanoic acid (OA) and Sy with the weight ratio of 20:80, 28:72 and 50:50 in order to obtain unsaturated mlcl-copolyesters coded PHO-Sy-2080, PHO-Sy-2872, and PHO-Sy-5050, respectively. The microorganism was also grown on the mixture of Sy and 10-undecenoic acid (UA) with the weight ratio of 50:50 to obtain unsaturated copolyester coded PHU-Sy-5050. The PHAs obtained were characteri . . .zed by 1H NMR and GC-MS techniques. Double bond contents of the unsaturated PHAs obtained were varying between 0.8 to 20 mol %. Autoxidation of the unsaturated copolyesters were carried out on exposure to air at room temperature in order to obtain new biomaterials whose mechanical strength was improved. Autoxidation kinetics, shelf life, mechanical and thermal properties of these biomaterials were evaluated Daha fazlası Daha az

Novel Enzymatic Rhodium Modified Poly(styrene-g-oleic amide) Film Electrode for Hydrogen Peroxide Detection

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

Article | 2017 | Electroanalysis29 ( 10 ) , pp.2377 - 2384

Newly synthesized poly(styrene-g-oleic amide) was coated onto a rhodium nanoparticle modified glassy carbon (GC) surface for the fabrication of horseradish peroxidase based biosensor used for hydrogen peroxide detection. The rhodium modifed electrode presented ten times higher signal than unmodified electrode even at low elecrtroactive enzyme quantity by enhancing the electron transfer rate at the applied potential of -0.65 V. The biosensor designed by under the optimized rhodium electrodeposition time exhibited a fast response less than 5 s, an excellent operational stability with a relative standard deviation of 0.6 % (n=6), an ac . . .curacy of 96 % and a large linear range between 50 µM and 120 mM for hydrogen peroxide. Detection limit and the sensitivity parameters were calculated to be 44 µM and 57 µA mM-1 cm-2, respectively by preserving its entire initial response up to the 15 days, while only 20 % of its initial response was lost at the end of one month. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei Daha fazlası Daha az

Determination of lead, copper, and iron in cosmetics, water, soil, and food using polyhydroxybutyrate-B-polydimethyl siloxane preconcentration and flame atomic absorption spectrometry

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

Article | 2015 | Analytical Letters48 ( 7 ) , pp.1163 - 1179

A separation and preconcentration method has been established based on solid phase extraction of Fe(III), Cu(II) and Pb(II) as their 2-(5-Bromo-2-pyridylazo)-5-diethylamino-phenol (5-Br-PADAP) chelates adsorbed on polyhydroxybutyrate-b-polydimethyl siloxane. Several analytical conditions including pH, amount of (5-Br-PADAP), eluent type and volume, sample volume, and flow rates were investigated. The effects of foreign ions on the recovery of the analytes were also studied. The detection limits for Cu(II), Fe(III), and Pb(II) were 1.9, 2.2, and 2.5 µg per liter, respectively. Enrichment factors for Cu(II), Fe(III), and Pb(II) were 1 . . .50, 200, and 80, respectively. The adsorption capacity of the polymer for Cu(II) and Pb(II) studied was 10.2 and 17.2 milligrams per gram respectively. Relative standard deviation was 4%. Standard Reference Material (SRM 1577B Bovine liver), International Atomic Energy Agency (IAEA 336 Lichen), and Certified Reference Waters for Trace Elements (TMDA 51.3 Fortified lake water) were used for the validation of the method. Optimized procedure was applied for the determination of analyte elements in various cosmetic products, hair brilliantine and gel, water, soil, and food samples from Turkey. © 2015, Copyright © Taylor & Francis Group, LLC Daha fazlası Daha az

Effect of the composition of methanol-water mixtures on tacticity of poly(N-ethylacrylamide) gel

Biswas, Chandra Sekhar | Sulu, Elvan | Hazer, Baki

Article | 2015 | Journal of Applied Polymer Science132 ( 12 ) , pp.1163 - 1179

Two series of macroporous poly(N-ethylacrylamide) (PNEAM) gels are synthesized in different composition of methanol-water mixtures (xm=0, 0.06, 0.13, 0.21, 0.31, and 0.43; where xm=mole fraction of methanol) in presence as well as in the absence of 0.1M Y(OTf)3 Lewis acid as additive. The gels synthesized in the absence of Lewis acid are atactic and in the presence of the same are isotactic. Synthesis of the corresponding linear PNEAM homopolymers shows that, the isotacticity (meso dyad, %) of the resulted polymers increases for the gels prepared in the presence of Lewis acid (LA) and remains constant for the gel prepared in the abs . . .ence of LA, respectively, with the increase in the concentration of the synthesis solvent methanol. SEM micrographs reveal that, the hydrogels synthesized in the presence of LA are more porous than the gels prepared in the absence of LA. Swelling ratio of all the hydrogels decreases with the increase in the temperature and LA gels show higher swelling ratio values than non LA gels (NLA). Deswelling rate of the hydrogels prepared in methanol-water mixture in presence of LA is faster than the hydrogels prepared in absence of LA. Moreover, reswelling rate increases with increase in the isotacticity of the PNEAM segment in the gel. All these results have been explained on the basis of the formation of highly porous hydrogels with higher isotactic PNEAM chain segment in the presence of LA in methanol-water mixtures. © 2014 Wiley Periodicals, Inc Daha fazlası Daha az

Poly(N-isopropylacrylamide) thermoresponsive cross-linked conjugates containing polymeric soybean oil and/or polypropylene glycol

Allı, Abdulkadir | Hazer, Baki

Article | 2008 | European Polymer Journal44 ( 6 ) , pp.1701 - 1713

Synthesis, characterization and solution properties of a new series of the PNIPAM-soybean oil and/or polypropylene glycol, PPG, conjugates (conjugates also referred to as co-networks) have been described. For this purpose free radical polymerization of NIPAM monomer was initiated by macroinitiators based on PSB and/or PPG in order to obtain PSB-g-PNIPAM, PPG-g-PNIPAM and PSB-g-PPG-g-PNIPAM cross-linked graft copolymers. The autooxidation of soybean oil under air at room temperature rendered waxy soluble polymeric soybean oil peroxide associated with cross-linked parts. The soluble polymeric oil macro-peroxide isolated from the cross . . .-linked part was used to initiate the free radical polymerization of NIPAM to give PSB-g-PNIPAM cross-linked copolymer. To obtain PPG-macromonomeric initiator, PPG-MIM, PPG-bis amino propyl ether with Mn 400 (or 2000) Dalton was reacted with 4,4'-azo bis cyanopentanoyl chloride and methacryloyl chloride, respectively. PPG-MIM also initiated the free radical polymerization of NIPAM at 80 °C to yield PPG-g-PNIPAM cross-linked thermoresponsive product. In order to obtain PSB-g-PPG-g-PNIPAM cross-linked triblock copolymer, NIPAM was polymerized by using the mixture of two macroinitiators, PSB and PPG-MIM. PSB contents in the graft copolymers were calculated via elemental analysis of nitrogen in graft copolymers. Thermal analysis, SEM, FTIR and 1H NMR techniques were used in the characterization of the products. The effect of polymeric soybean oil, PSB, and/or PPG on the thermal response rate of poly(N-isopropylacrylamide, PNIPAM, cross-linked-graft copolymers swollen in water has been investigated by means of swelling-deswelling and drug release behaviors against to temperature change. Lower critical solution temperatures (LCST) of the cross-linked PNIPAM conjugates (conjugates also referred to as co-networks) were determined from the curves of swelling degrees versus solution temperatures. The response temperature of the hydrophobically modified PNIPAM conjugates was reduced to 27 °C, 23 °C and 27 °C for PSB-g-PNIPAM, PPG-g-PNIPAM and PSB-g-PPG-g-PNIPAM, respectively. We have found that the graft copolymers were not pH-responsive. In addition, higher pH ranges cause the hydrolysis of the PSB ester linkages, quickly and makes the cross-linked graft copolymers soluble. The fastest shrinking of the gels was observed by loosing water between 65% and 98% at 50 °C. Methyl orange (MO), was used as a model drug, loaded into cross-linked graft copolymers to examine and compare the effects of controlled release at lower and higher temperatures of lower critical solution temperature (LCST). © 2008 Elsevier Ltd. All rights reserved Daha fazlası Daha az

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