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Öğe Biodegradable Poly(epsilon-Caprolactone)-Based Graft Copolymers Via Poly(Linoleic Acid): In Vitro Enzymatic Evaluation(Springer, 2015) Allı, Sema; Aydın, Rahime Seda Tığlı; Allı, Abdulkadir; Hazer, BakiWell-defined graft copolymers based on poly(epsilon-caprolactone) (PCL) via poly(linoleic acid) (PLina), are derived from soybean oil. Poly(linoleic acid)-g-poly(epsilon-caprolactone) (PLina-g-PCL) and poly(linoleic acid)-g-poly(styrene)-g-poly(epsilon-caprolactone) (PLina-g-PSt-g-PCL) were synthesized by ring-opening polymerization of epsilon-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.Öğe Hyperbranched homo and thermoresponsive graft copolymers by using ATRP-macromonomer initiators(Wiley, 2012) Allı, Sema; Allı, Abdulkadir; Hazer, BakiMacromonomer initiators behave as macro cross-linkers, macro initiators, and macromonomers to obtain branched and cross-linked block/graft copolymers. A series of new macromonomer initiators for atom transfer radical polymerization (MIM-ATRP) based on polyethylene glycol (M-n = 495D, 2203D, and 4203D) (PEG) were synthesized by the reaction of the hydroxyl end of mono-methacryloyl polyethylene glycol with 2-bromo propanoyl chloride, leading to methacryloyl polyethylene glycol 2-bromo propanoyl ester. Poly (ethylene glycol) functionalized with methacrylate at one end was reacted with 2-bromopropionyl chloride to form a macromonomeric initiator for ATRP. ATRP was found to be a more controllable polymerization method than conventional free radical polymerization in view of fewer cross-linked polymers and highly branched polymers produced from macromonomer initiators as well. In another scenario, ATRP of N-isopropylacrylamide (NIPAM) was initiated by MIM-ATRP to obtain PEG-b-PNIPAM branched block/graft copolymers. Thermal analysis, FTIR, H-1 NMR, TEM, and SEM techniques were used in the characterization of the products. They had a thermo-responsive character and exhibited volume phase transition at similar to 36 degrees C. A plasticizer effect of PEG in graft copolymers was also observed, indicating a lower glass transition temperature than that of pure PNIPAM. Homo and copolymerization kinetics were also evaluated. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012Öğe Nitroxide-mediated copolymerization of styrene and pentafluorostyrene initiated by polymeric linoleic acid(Wiley, 2016) Allı, Abdulkadir; Allı, Sema; Becer, C. Remzi; Hazer, BakiPolymeric 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 reactions, were evaluated. The products thus obtained were well characterized by H-1 NMR, GPC, and F-19 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. NMRPreactions 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).Öğe One-Pot Synthesis of Poly(linoleic acid)-g-Poly(styrene)-g-Poly(epsilon-caprolactone) Graft Copolymers(Springer, 2014) Allı, Abdulkadir; Allı, Sema; Becer, C. Remzi; Hazer, BakiOne-pot synthesis of graft copolymers by ring-opening polymerization and free radical polymerization using polymeric linoleic acid peroxide (PLina) is reported. Graft copolymers having structures of poly(linoleic acid)-g-polystyrene-g-poly(epsilon-caprolactone) were synthesized from PLina, possessing peroxide groups on the main chain by the combination of free radical polymerization of styrene and ring-opening polymerization of epsilon-caprolactone in one-step. Principal parameters, such as monomer concentration, initiator concentration, and polymerization time, which effect the one-pot polymerization reactions were evaluated. The obtained graft copolymers were characterized by H-1-NMR and DOSY-NMR spectroscopy, gel permeation chromatography, thermal gravimetric analysis and differential scanning calorimetry techniques.Öğe Redox polymerization of N-isopropylacrylamide by using hydroxylated soya oil polymer(Scientific Technical Research Council Turkey-Tubitak, 2015) Allı, Abdulkadir; Sanal, Timur; Hazer, BakiWater soluble hydroxylated soya oil polymer was used in the redox polymerization of N-isopropylacrylamide (NIPAM) in order to obtain water-based hydroxylated-soya oil polymer-g-PNIPAM graft copolymer. For this purpose, soya oil was exposed to air under sunlight to obtain autoxidized soya oil polymer (PSy-ox). PSy-ox was allowed to react with diethanol amine to obtain hydroxylated soya oil polymer (hydroxylated-PSy). An ammonium persulfate with hydroxylated-PSy redox initiating system was used in the polymerization of NIPAM in order to obtain thermoresponsive hydroxylated-PSy-g-PNIPAM water-based graft copolymers. The graft copolymers were characterized using proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, gel permeation chromatography, thermal gravimetric analysis, and differential scanning calorimetry techniques. The effects of hydroxylated-PSy on the thermal response rate of PNIPAM and the percentage of transmittance in the water of graft copolymers were studied by means of observing UV transmittance behaviors in response to changing temperature. This showed the temperature-responsive property, and exhibited a volume phase transition from 22 degrees C to 29 degrees C, while that of PNIPAM was 32 degrees C.Öğe Synthesis and Characterization of Poly(N-Isopropyl Acryl Amide)-g-Poly(Linoleic Acid)/Poly(Linolenic Acid) Graft Copolymers(Springer, 2011) Allı, Abdulkadir; Hazer, BakiTo diversify edible oil thermoresponsive polymer composites, polymeric linoleic acid peroxide (PLina) and polymeric linolenic acid peroxide (PLinl) were obtained by the autoxidation of linoleic acid (Lina) and linolenic acid (Linl), respectively. The autoxidation of Lina and Linl under air at room temperature rendered waxy soluble polymeric peroxide, having a soluble fraction in chloroform of more than 91 wt% and containing up to 1.0 wt% of peroxide. The soluble polymeric oil macro-peroxide was used to initiate the free radical polymerization of N-isopropylacrylamide, NIPAM, resulting in PLina-g-PNIPAM and PLinl-g-PNIPAM graft copolymers, respectively. The PNIPAM content of the graft copolymers was calculated using the elemental nitrogen analysis of graft copolymers. Thermal analysis, FTIR, (1)H NMR, and SEM techniques were used in the characterization of the products. The hydrophobic effect of the fatty acid macro peroxides on the thermal response rate of the graft copolymers was investigated by means of swelling-deswelling behaviors in response to temperature change. They have a thermoresponsive character and exhibit a volume phase transition at approximately 27-30 A degrees C, which is 1-4 A degrees C lower than that of pure PNIPAM. A plastizer effect of PLina and PLinl in graft copolymers was observed, indicating a lower glass transition temperature than that of pure PNIPAM.Öğe Synthesis and characterization of star-shaped block copolymers composed of poly(3-hydroxy octanoate) and styrene via RAFT polymerization(Taylor & Francis Inc, 2022) Allı, Abdulkadir; Allı, Sema; Hazer, Baki; Zinn, ManfredThis study investigated a macro reversible addition fraction chain transfer (RAFT) agent based on three-arm hydroxylated star-shaped poly(3-hydroxy octanoate). The utilization of this star-shaped poly(3-hydroxy octanoate) macro-RAFT agent in the RAFT process resulted in efficient control in the preparation of star-shaped block styrene copolymers. Poly(3-hydroxy octanoate) (PHO) was reacted with diethanol amine (DEA) in order to obtain three-arm hydroxylated poly(3-hydroxy octanoate) (PHO-DEA). A carboxylic acid-functionalized RAFT agent (2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid) was reacted with the PHO-DEA in order to obtain a star-shaped PHO macro-RAFT agent (PHO-R2). A series of AB(3) type PHO-polystyrene (PHO-PS) star-shaped block copolymers were obtained via the polymerization of styrene (S) using the PHO-R2 in toluene at 80 degrees C. The RAFT polymerization was seen to obey the polymerization kinetics of controlled free radical polymerization. The plasticizing effect of the PHO soft segments was influenced by the glass transition temperature (Tg) of polystyrene. This was clearly observed in the block copolymers. Moreover, it was clear that this plasticizing effect disappeared in the block copolymers as a result of the increase in polymerization time. The molar masses of the obtained copolymers increased in parallel with increases in the polymerization time. Structural, physiochemical, and thermal characterization of the obtained products was carried out using size-exclusion chromatography (SEC), proton nuclear magnetic resonance (H-1 NMR), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA) techniques. The polymerization kinetics of the star-shaped block copolymers were also investigated in detail.Öğe Synthesis and physicochemical characterization of PMMA and PNIPAM based block copolymers by using PEG based macro RAFT agents(Indian Acad Sciences, 2022) Senemoğlu, Yetkin; Hazer, Baki; Arslan, Hülya; Allı, Abdulkadir; Allı, Sema; Şen, SadiPolyethylene glycol (PEG) based macro-RAFT agents were synthesized by the condensation reaction of PEG (Mn: 2000 Da and 8000 Da) with the carboxylic acid functionalized trithiocarbonate [S-Dodecyl-S'-(alpha,alpha'-dimethyl-alpha ''-acetic acid) tritiocarbonate (DDMAT)] using dicyclohexylcarbodiimide (DCC)/4-(dimethylamino) pyridine (DMAP) as catalyst at room temperature. Then, N-isopropylacrylamide (NIPAM) and methyl methacrylate (MMA) monomers were polymerized, respectively, using synthesized new macro-RAFT agents and N, N'-azo bis isobutyronitrile (AIBN) as the initiator. In all RAFT polymerizations, dispersity values were found in the range of 1.04 to 1.47, which showed that RAFT polymerization was applied successfully. The synthesized polymers were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Proton Nuclear Magnetic Resonance Spectroscopy (H-1-NMR), Gel Permeation Chromatography (GPC) and Differential Scanning Calorimetry (DSC) techniques. The fractured surface images of PEG-b-PMMA block copolymers were obtained by Scanning Electron Microscopy (SEM). SEM images PEG-b-PMMA block copolymers have shown that the copolymers have a microporous structure. In addition, the swelling ratios and LCST values of the PEG-b-PNIPAM block copolymers were measured which were found to be very high. The lower critical temperature values of the copolymers are closer to that of the PNIPAM homopolymer, 32 degrees C, indicating its usability in drug delivery systems.Öğe Telechelic polyhydroxyalkanoates/polyhydroxybutyrates (PHAs/PHBs)(Pan Stanford Publishing Pte. Ltd., 2017) Allı, Abdulkadir; Hazer, Baki; Adamus, G.; Kowalczuk, MarekPoly(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.Öğe UV illumination effects on electrical characteristics of metal-polymer-semiconductor diodes fabricated with new poly(propylene glycol)-b-polystyrene block copolymer(Elsevier Sci Ltd, 2014) Gökçen, Muharrem; Yıldırım, Mert; Demir, Ahmet; Allı, Abdulkadir; Allı, Sema; Hazer, BakiAu/poly(propylene glycol)-b-polystyrene/n-Si (D1) and Au/poly(propylene glycol)-b-polystyrene(HAuCl4 dispersed)/n-Si (02) 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/cm(2)). 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/cm(2) 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 similar to 10(3) times with 100 mW/cm(2) UV illumination for both diodes. Furthermore, density distribution profiles of surface states in these diodes were also investigated. (C) 2013 Elsevier Ltd. All rights reserved.
