Bulunan: 8 Adet 0.002 sn
Koleksiyon [16]
Tam Metin [2]
Yayın Türü [1]
Yazar [20]
Yayın Yılı [5]
Konu Başlıkları [20]
Yayın Dili [1]
Dergi Adı [3]
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

Synthesis of novel biodegradable elastomers based on poly[3-hydroxy butyrate] and poly[3-hydroxy octanoate] via transamidation reaction

Hazer, Baki | Akyol, Elvan | Şanal, Timur | Guillaume, Sophie | Çakmaklı, Birten | Steinbuchel, Alexander

Article | 2019 | Polymer Bulletin76 ( 2 ) , pp.919 - 932

Poly(3-hydroxyalkanoate)s (PHAs) are a class of polymers receiving attention because of their potential as renewable, biodegradable and high-technology properties. Unlike most short chain length (scl) PHAs such as poly(3-hydroxybutyrate) (PHB), medium chain length (mcl) PHAs such as poly(3-hydroxyoctanoate) (PHO) exhibit low crystallinity and are elastomeric in character. PHB-b–PEG-b–PHO block copolymers can combine both properties in block copolymer matrix. In this study, we report the synthesis of the block copolymers combining the PHB and PHO blocks. Transamidation reactions of PHB with polyethylene glycol with primary amine yiel . . .d equimolar amounts and PHB with amine ends. PHO reacts with the modified PHB containing the amine end to give PHB-b–PEG-b–PHO block copolymers. Structural analysis of the products was performed by using 1H–, 13C, heteronuclear single quantum coherence NMR techniques. Thermal and mechanical properties of the block polymers were also evaluated. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature Daha fazlası Daha az

γ-Ray induced graft copolymerization of methyl methacrylate onto poly(ß-hydroxynonanoate)

Eroğlu, Mehmet S. | Çaykara, Tuncer | Hazer, Baki

Article | 1998 | Polymer Bulletin41 ( 1 ) , pp.53 - 60

Copolymers of poly(3-hydroxy-nonanoate), PHN, with methyl methacrylate, MMA, were prepared using 60Co-gamma irradiator. The bulk solutions of PHN in MMA were prepared at different PHN feed concentration and they were irradiated to 8.5 kGy at room temperature. Polymer fractions obtained by solvent-nonsolvent fractional precipitation were carefully characterized using gel permeation chromatography (GPC), nuclear magnetic resonance spectroscopy (NMR), and thermal gravimetric analysis (TGA) techniques. High copolymerization yield was observed and the copolymer compositions obtained from the TGA measurements were consistent with the NMR . . .results. PHN contents of the copolymer samples changed from 5 to 35 wt.-%. The strain at break and tensile strength values of copolymers were between the values of their respective homopolymers. It was observed that pure copolymer samples showed up to 13% strain at break Daha fazlası Daha az

Biodegradable poly(ε-caprolactone)-based graft copolymers via poly(linoleic acid): In vitro enzymatic evaluation

Allı, Sema | Tığlı-Aydın, Rahime Seda | Allı, Abdülkadir | Hazer, Baki

Article | 2015 | JAOCS, Journal of the American Oil Chemists' Society92 ( 3 ) , pp.449 - 458

Well-defined graft copolymers based on poly(?-caprolactone) (PCL) via poly(linoleic acid) (PLina), are derived from soybean oil. Poly(linoleic acid)-g-poly(?-caprolactone) (PLina-g-PCL) and poly(linoleic acid)-g-poly(styrene)-g-poly(?-caprolactone) (PLina-g-PSt-g-PCL) were synthesized by ring-opening polymerization of ?-caprolactone initiated by PLina and one-pot synthesis of graft copolymers, and by ring-opening polymerization and free radical polymerization by using PLina, respectively. PLina-g-PCL, PLina-g-PSt-g-PCL3, and PLina-g-PSt-g-PCL4 copolymers containing 96.97, 75.04 and 80.34 mol% CL, respectively, have been investigated . . . regarding their enzymatic degradation properties in the presence of Pseudomonas lipase. In terms of weight loss, after 1 month, 51.5% of PLina-g-PCL, 18.8% of PLina-g-PSt-g-PCL3, and 38.4% of PLina-g-PSt-g-PCL4 were degraded, leaving remaining copolymers with molecular weights of 16,140, 83,220 and 70,600 Da, respectively. Introducing the PLina unit into the copolymers greatly decreased the degradation rate. The molar ratio of [CL]/[Lina] dramatically decreased, from 21.3 to 8.4, after 30 days of incubation. Moreover, reduced PCL content in PLina-g-PSt-g-PCL copolymers decreased the degradation rate, probably due to the PSt enrichment within the structure, which blocks lipase contact with PCL units. Thus, copolymerization of PCL with PLina and PSt units leads to a controllable degradation profile, which encourages the use of these polymers as promising biomaterials for tissue engineering applications. © AOCS 2015 Daha fazlası Daha az

Biodegradable and biocompatible radiopaque iodinated poly-3-hydroxy butyrate: synthesis, characterization and in vitro/in vivo X-ray visibility

Erol, Arzu | Rosberg, Derya B. Hazer | Hazer, Baki | Göncü, Beyza S.

Article | 2019 | Polymer Bulletin , pp.449 - 458

Some novel radiopaque biodegradable and biocompatible iodinated polymers based on poly-3-hydroxy butyrate (PHB) were obtained. Following the attachment of diethanol amine to PHB, the hydroxyl ends were capped with 4-iodobenzoic acid and 2,3,5-tri-iodobenzoic acid. In this manner, tri-novel radiopaque polymers were obtained. The resulting polymers were structurally characterized by NMR technique. They were evaluated with respect to their possible use as radiopaque implant biomaterials indicating X-ray visibility in a noninvasive manner using routine X-ray absorption imaging techniques. These polymers exhibited good radiopacity with c . . .onventional imaging X-ray techniques in vivo. Additionally, biocompatibility of these iodinated polymers was also evaluated. There were no signs of infection or abscess formation on the surgical area. These novel radiopaque PHBs should be promising biomaterials for a new-generation radiopaque materials. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature Daha fazlası Daha az

Effects of polymer-based, silver nanoparticle-coated silicone splints on the nasal mucosa of rats

Şevik Eliçora, Sultan | Erdem, Duygu | Dinç, Aykut Erdem | Altunordu Kalaycı, Özlem | Hazer, Baki | Yurdakan, Gamze | Külah, Canan

Article | 2017 | European Archives of Oto-Rhino-Laryngology274 ( 3 ) , pp.1535 - 1541

Infection is a serious complication after nasal packing that otolaryngologists seek to avoid. The aim of this study is to investigate the use of silver (Ag) nanoparticle, which serves as antimicrobial agents, with nasal tampons. The study design is an experimental animal model and the setting is tertiary referral center. Twenty-four rats were randomized into the following four groups: (1) control group (n = 6); (2) silicone nasal splint (SNS) group (n = 6); (3) polypropylene-grafted polyethylene glycol (PP-g-PEG) amphiphilic graft copolymer-coated SNS group (n = 6); and (4) Ag nanoparticle-embedded PP-g-PEG (Ag-PP-g-PEG) amphiphilic . . . graft copolymer-coated SNS group (n = 6). These tampons were applied to rats for 48 h, after which they were removed in a sterile manner, and the rats were sacrificed. The nasal septa of the rats were excised, and assessments of tissue changes in the nasal mucosa were compared among the groups. The removed tampons were microbiologically examined, and quantitative analyses were made. When the groups were compared microbiologically, there were no significant differences in bacterial colonization rates of coagulase-negative Staphylococcus spp. among the three groups (p = 0.519), but there was a statistically significant difference among bacterial colonization rates of Heamophilus parainfluenzae and Corynebacterium spp. (p = 0.018, p = 0.004). We found that H. parainfluenzae grew less robustly in the Ag-PP-g-PEG than the PP-g-PEG group (p = 0.017). However, we found no significant difference between the Ag-PP-g-PEG and SNS groups, or between the SNS and PP-g-PEG groups. The growth of Corynebacterium spp. did not differ significantly between the Ag-PP-g-PEG and SNS groups (p = 1.000). When Group 4 was compared with Group 2, the former showed less inflammation. Compared with other tampons, Ag-PP-g-PEG amphiphilic graft copolymer-coated silicone nasal tampons caused less microbiological colonization and inflammation. Therefore, the use of these tampons may prevent secondary infections and reduce the risk of developing complications by minimizing tissue damage. © 2016, Springer-Verlag Berlin Heidelberg Daha fazlası Daha az

Efficiency of gold nano particles on the autoxidized soybean oil polymer: fractionation and structural analysis

Hazer, Baki | Akyol, Elvan

Article | 2016 | JAOCS, Journal of the American Oil Chemists' Society93 ( 2 ) , pp.201 - 213

Polyunsaturated plant oils have gained great interest as monomers to produce biodegradable polymers obtained from renewable resources due to the limited existing sources of petroleum oil and environmental issues. Soybean oil was autoxidized by exposure to atomospheric oxygen at room temperature with or without the presence of gold nanoparticles (Au NPs) 5-41 days. When the autoxidation process was catalyzed with Au NPs, the molecular weight of the oxidized oil was increased in 5 days. In contrast to this, without Au NPs, the oxidized oil was still a fluidized liquid. Autoxidized soybean oil polymer in toluene solution with gold NP s . . .howed a surface plasmon resonance at ?max = 540 nm in a UV-VIS spectrometer and a fluorescence emission spectrum at ?max = 450 nm, when it was irradiated at ?max = 390 nm. The higher molecular weight of the polymeric oils was successively fractionated by the extraction from the solvent-non-solvent mixture CHCl3/petroleum ether with the volume ratio of 5:15. Three polymeric oils fractions with different molecular weight (ca 1000, 4000, and 40,000 g/mol) were obtained. GC-MS analysis, 1H-NMR and GPC techniques were used in the structural analysis of the fractionated polymeric oils. © 2015 AOCS Daha fazlası Daha az

Influence of Soybean Oil Blending with Polylactic Acid (PLA) Films: In Vitro and In Vivo Evaluation

Aydın, R. Seda Tığlı | Akyol, Elvan | Hazer, Baki

Article | 2017 | JAOCS, Journal of the American Oil Chemists' Society94 ( 3 ) , pp.413 - 424

Due to the great interest in oil-based polymers, which are prepared from renewable resources, different forms and amounts of soybean oil-based PLA films were prepared and evaluated for their potential usage as a medical biomaterial. Soybean oil, epoxidized soybean oil and auto-oxidized soybean oil were blended with PLA and PLA/oil films with appropriate oil amounts [2, 7, 14 and 20% (w/w)] were obtained by solvent casting. Thermal stability and plasticization effect were determined by adjusting oil amounts and type. Epoxidized soybean oil blended films showed the smallest increase in elongation breaks (13–20%) and the highest decrea . . .se in thermal decomposition temperatures (364–327 °C) compared to other oil blended films. In vitro quantitative and qualitative cytotoxicity results showed no reactivity (grade 0) for the L929 cells treated with 14% (w/w) oil blended PLA films. In vivo irritation and implantation tests concluded that 14% (w/w) oil blended PLA films were non-irritant. No erythema, no oedema reactions, no traumatic necrosis and foreign debris were observed. Thus, along with superior biocompatibility, PLA/oil films can replace petroleum-based products for several biomedical uses. © 2017, AOCS Daha fazlası Daha az

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