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Öğe Biocompatible multi-walled carbon nanotube-CdTe quantum dot-polymer hybrids for medical applications(ELSEVIER SCIENCE BV, 2015) Başlak, Canan; Kars, Meltem Demirel; Karaman, Mustafa; Kuş, Mahmut; Çengeloğlu, Yunus; Ersöz, MustafaHerein we report the synthesis of polymer coated quantum dots (QDs)-carbon nanotube composite material with high biocompatibility and low cellular toxicity. The synthesized multi-walled carbon nanotube (MWCNT)-QD-(-poly(glycidyl methacrylate)) (pGMA) hybrids were characterized using X-ray photoelectron spectroscopy, laser scanning confocal microscopy, transmission electron microscopy and scanning electron microscopy. The results showed that quantum dots were well-distributed on nanotube surfaces in high density. The toxicological assessments of QDs and MWCNT-QD-polymer hybrids in human mammary carcinoma cells and their fluorescence imaging in living cell system were carried out. MWCNT-QD-polymer hybrids possess intense red fluorescence signal under confocal microscopy and good fluorescence stability over 6-h exposure in living cell system. The toxicity comparison of QDs and MWCNT-QD-polymer hybrids has shown that the existence of PGMA thin coating on MWCNT-QD hybrid surface decreased the cellular toxicity and increased biocompatibility. (C) 2014 Elsevier B.V. All rights reserved.Öğe Chemical and Physical Modification of Surfaces(WILEY-V C H VERLAG GMBH, 2017) Karaman, Mustafa; Gursoy, Mehmet; Kus, Mahmut; Ozel, Faruk; Yenel, Esma; Sahin, Ozlem G.; Kivrak, Hilal D.[Abstract not Available]Öğe Chemical and plasma surface modification of lignocellulose coconut waste for the preparation of advanced biobased composite materials(ELSEVIER SCI LTD, 2017) Kocaman, Suheyla; Karaman, Mustafa; Gursoy, Mehmet; Ahmetli, GulnareIn this study, surface-modified grinded coconut waste (CW) particles were used as bio-fillers to prepare polymeric composite materials with enhanced properties. Epoxy resin modified with acrylated and epoxidized soybean oil (AESO) was used as the polymer matrix. Two different strategies, namely chemical treatment and plasma enhanced chemical vapor deposition (PECVD) were utilized to modify the surface of CW particles for using them as compatible bio-fillers in composite preparation. Chemical modification involved the treatment of CW particles in a highly alkali NaOH solution, while PECVD modification involved coating of a thin film of hydrophobic poly(hexafluorobutyl acrylate) (PHFBA) around individual CW particle surfaces. Untreated and surface-modified CW particles were used in 10-50 wt% for preparation of epoxy composites. FTIR analysis was performed to study the effect of modification on the structures of particles and as-prepared composites. The composite morphologies were investigated by XRD and SE. TGA test was conducted to study the thermal behavior of the composites. Also, the effects of CW particle surface modification on the mechanical and water sorption properties of epoxy resin composites were investigated in detail. It was observed that PECVD-treated CW particles had much more positive effects on the thermal, mechanical, wettability and flammability properties of composites. (C) 2016 Elsevier Ltd. All rights reserved.Öğe Determination of homogenization performance of grinder used for aflatoxin analyses of Turkish hazelnuts(2009) Baltacı, Cemalettin; Kara, Meryem; Aliyazıcıoğlu, Rezzan; Kolaylı, Sevgi; Karaman, Mustafa; Yıldız, OktayThis research was conducted to determine the homogeneity performance of laboratory grinder used for aflatoxin (Aflatoxin B1: AFB1; Aflatoxin B2: AFB2; Aflatoxin G1: AFG1; Aflatoxin G2: AFG2) analysis of hazelnut, one of the strategic products from the Black Sea Region. For the research, naturally aflatoxins-contaminated hazelnut samples in their unshelled state (A) and non-contaminated unshelled hazelnut samples (B) were used. Hazelnut samples in which aflatoxin (AFs) couldn't be detected by the analytical procedure were treated with standard solutions of 10 pg mL-1 AFB1, 5 pg mL"1 AFB2, 10 pg mL"1 AFG1, 5 pg mL"1 AFG2 at the levels of 2 mL, 0.6 mL, 4 mL and 1 mL, respectively. Then, hazelnut samples treated with AFs were grounded in laboratory grinders after 30 min of resting. The Cochran test procedure was applied to duplicate results to determine sufficient homogeneity of grinder. Variations among samples in both hazelnut groups were smaller than critical value of the statistical procedure of the Cochran test.Öğe Effect of noncovalent chemical modification on the electrical conductivity and tensile properties of poly(methyl methacrylate)/carbon nanotube composites(WILEY-BLACKWELL, 2013) Koysuren, Ozcan; Karaman, Mustafa; Ozyurt, DemetNoncovalent chemical modification by initiated chemical vapor deposition technique is applied to carbon nanotubes (CNTs) to reduce average agglomerate size of the nanoparticles in the polymer matrix and to improve surface interaction between the composite constituents. CNT surfaces are coated conformally with thin poly(glycidyl methacrylate) (PGMA) polymer film and coated nanoparticles are incorporated in poly(methyl methacrylate) (PMMA) polymer matrix using solvent casting technique. Conformal PGMA coatings around individual nanotubes were identified by scanning electron microscopy analysis. Transmission electron microscopy and optical microscopy analyses show homogeneous composite morphology for composites prepared by using PGMA coated nanotubes. Fourier Transform Infrared and X-ray photoelectron spectroscopy analyses show the successful deposition of polymer with high retention of epoxide functionality. PGMA coating of CNTs exhibits improvement in electrical conductivity and tensile properties of PGMA-CNT/PMMA systems when compared with uncoated nanoparticles. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013Öğe Effect of substrate temperature on initiated plasma enhanced chemical vapor deposition of PHEMA thin films(VERLAG DR KOSTER, 2015) Gursoy, Mehmet; Karaman, MustafaPoly(2-hydroxyethyl methacrylate) (PHEMA) thin films were deposited on silicon wafers by initiated plasma enhanced chemical vapour deposition (i-PECVD) method at different substrate temperatures. Di tert-butyl peroxide (TBPO) was used as an initiator, and all deposition experiments were performed at 3: 1 monomer to initiator flow ratio. Deposition rates up to 44 nm/min were observed at relatively low plasma power depending on the deposition conditions. The high deposition rates at low plasma powers were attributed to the usage of the initiator. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses of the deposits indicated very high retention of hydroxyl and carbonyl functionalities especially for the polymers deposited at low plasma powers. Water contact angle measurements were carried out to determine the wettability of as-deposited PHEMA surfaces. This study indicated that the substrate temperature is an important parameter determining the polymerization rate. Being a dry, low-cost, reliable and environmentally friendly process, the i-PECVD technique developed in this study can be used to deposit other functional polymers. The water contact angle measurement images of PHEMA thin films at different substrate temperatures. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimÖğe Electrospun Polyvinyl Borate/Poly(methyl methacrylate) (PVB/PMMA) Blend Nanofibers(TAYLOR & FRANCIS AS, 2014) Koysuren, Ozcan; Karaman, Mustafa; Yildiz, Huseyin Bekir; Koysuren, H. Nagehan; Dinc, HavvaThe aim of this study was to prepare polyvinyl borate (PVB)/poly(methyl methacrylate) (PMMA) blend nanofibers by electrospinning process. Polyvinyl borate was synthesized by the condensation reaction of polyvinyl alcohol and boric acid. FTIR analyses showed that boron atoms were found to be integrated into the polymer network. Blending PMMA with PVB decreased the fiber diameter and enhanced the surface roughness of PVB/PMMA blend nanofiber mats. The water wetting property of the nanofiber mats was influenced by the surface roughness. The blend composition with the highest polyvinyl borate content was found to be suitable for thermally stable nanofiber formation.Öğe Enhanced mechanical properties of low-surface energy thin films by simultaneous plasma polymerization of fluorine and epoxy containing polymers(ELSEVIER SCIENCE BV, 2016) Karaman, Mustafa; Ucar, TubaThin films of poly(2,2,3,4,4,4 hexafluorobutyl acrylate-glycidyl methacrylate) (P(HFBA-GMA) were deposited on different surfaces using an inductively coupled RF plasma reactor. Fluorinated polymer was used to impart hydrophobicity, whereas epoxy polymer was used for improved durability. The deposition at a low plasma power and temperature was suitable for the functionalization of fragile surfaces such as textile fabrics. The coated rough textile surfaces were found to be superhydrophobic with water contact angles greater than 150 due to the high retention of long fluorinated side chains. The hydrophobicity of the surfaces was observed to be stable after many exposures to ultrasonification tests, which is attributed to the mechanical durability of the films due to their epoxide functionality. FTIR and XPS analyses of the deposited films confirmed that the epoxide functionality of the polymers increased with increasing glycidyl methacrylate fraction in the reactor inlet. The modulus and hardness values of the films also increase with increasing epoxide functionality. (C) 2015 Elsevier B.V. All rights reserved.Öğe Hydrophobic coating of expanded perlite particles by plasma polymerization(ELSEVIER SCIENCE SA, 2016) Gursoy, Mehmet; Karaman, MustafaIn this study, an RF plasma discharge was employed to deposit thin poly(hexafluorobutyl acrylate) (PHFBA) polymeric films on expanded perlite. A rotating plasma reactor was used to provide effective agitation and mixing of the particles during the depositions. Surface of expanded perlite, a hydrophilic porous material, was successfully transformed into super-hydrophobic due to the highly fluorinated chain of PHFBA. Deposition rates up to 42 nm/min were observed. The influences of plasma discharge conditions on wettability and water holding capacity of expanded perlite powders were investigated. Chemical and morphological properties of uncoated and coated expanded perlites were determined by SEM (EDS), FTIR, and contact angle measurements analyses. It is observed that the pulsed plasma approach helps to minimize undesirable monomer fragmentation while providing better film structure. It also should be emphasized that PECVD experiments did not change the morphology of the expanded perlite powders. The water holding capacity of expanded perlite was decreased from 70% down to around 4% upon coating on pulsing mode. (C) 2015 Elsevier B.V. All rights reserved.Öğe Hydrophobic coating of surfaces by plasma polymerization in an RF plasma reactor with an outer planar electrode: synthesis, characterization and biocompatibility(IOP PUBLISHING LTD, 2017) Karaman, Mustafa; Gursoy, Mehmet; Aykul, Fatmanur; Tosun, Zahide; Kars, M. Demirel; Yildiz, H. BekirThis paper presents the plasma polymerization of poly(hexafluorobutyl acrylate) (PHFBA) thin films on different substrates in an RF plasma reactor with an outer planar electrode. This reactor configuration allows. large area uniformity and fast processing times. Deposition rates of up to 60 nm min(-1) were observed. The influence. of plasma power and substrate temperature on the. deposition rate, structure and wettability of the as-deposited films was. investigated. It was observed that better hydrophobicity was obtained at high plasma power and in low temperature conditions. PHFBA thin films deposited on electrospun poly(acrylonitrile) fiber mats under such conditions resulted in superhydrophobic surfaces with. contact angle values greater than 150 degrees. In. vitro cell studies using human epithelial cells demonstrated the non-toxic nature of the. plasma-polymerized PHFBA films.Öğe Improvement of wetting properties of expanded perlite particles by an organic conformal coating(ELSEVIER SCIENCE SA, 2018) Gursoy, Mehmet; Karaman, MustafaExpanded perlite particles were surface functionalized using poly(hydroxyethyl methacrylate) (PHEMA) thin film under radio frequency (RF) plasma conditions in a rotating-bed plasma enhanced chemical vapor deposition (PECVD) system. Using a rotating-bed system allowed effective agitation and mixing of the particles during depositions, which ensure uniform surface coating of highly porous and particulate materials. The effects of plasma power and plasma operation mode, namely pulsed and continuous modes on the deposition rates, structure, wettability and water holding capacities of expanded perlite particles were investigated. Chemical and morphological properties of uncoated and coated expanded perlites were determined by SEM, FUR, contact angle, and BET analyses. Observed deposition rates changed between 10 and 35 nm/min., which were dependent on the deposition conditions. It was found that pulsing the discharge helped to minimize undesirable monomer fragmentation while providing better film structure. The most hydrophilic PHEMA thin films were fabricated at 50 W plasma power and under pulsed-plasma mode. When the expanded perlite was modified with PHEMA under suitable experimental conditions, the water holding capacity of untreated particles is increased by more than twenty percent.Öğe Initiated CVD of Tertiary Amine-Containing Glycidyl Methacrylate Copolymer Thin Films for Low Temperature Aqueous Chemical Functionalization(WILEY-V C H VERLAG GMBH, 2014) Sariipek, Fatma; Karaman, MustafaThis manuscript reports on the synthesis of copolymer films of glycidyl methacrylate with diethylaminoethyl methacrylate by initiated (i)CVD. The purpose of the incorporation of tertiary amine functionality in the copolymer film is to accelerate the rate of the nucleophilic ring-opening reaction of the epoxide group under benign conditions. It is found that tertiary amine functionality in the poly(glycidyl methacrylate) (PGMA) film significantly increases the rate and degree of the ring-opening reactions. After 2 h of reaction at room temperature, 72% of the epoxy groups are consumed, while the conversion under similar conditions is negligible for the PGMA film.Öğe INITIATED PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION (i-PECVD) OF POLY(ALKYL ACRYLATES)(IEEE, 2015) Karaman, Mustafa; Gursoy, Mehmet; Ucar, Tuba; Demir, Emrah; Yenice, Ezgi[Abstract not Available]Öğe Initiation of 2-Hydroxyethyl Methacrylate Polymerization by Tert-Butyl Peroxide in a Planar PECVD System(WILEY-V C H VERLAG GMBH, 2016) Gursoy, Mehmet; Ucar, Tuba; Tosun, Zahide; Karaman, MustafaThis article reports on the deposition conditions and characterization of poly(2-hydroxyethyl methacrylate) thin films grown by initiated plasma enhanced chemical vapor deposition process. The plasma power is inductively coupled into the process chamber with a planar-coil antenna through a quartz window, and the substrate is cooled to promote physical adsorption of monomers on its surface. The introduction of the initiator allowed for film deposition at very low plasma powers (1W) and greatly improves the deposition rates. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses confirmed that the chemical functionalities of the monomers are preserved to a good extent during the depositions that were carried out at low plasma powers. The deposition kinetics of PECVD-produced films from HEMA can be tailored by varying the substrate temperature. The apparent activation energies observed from PHEMA deposition kinetics with varying substrate temperatures are observed to be negative, which supports the hypothesis of the free radical polymerization mechanism in the PECVD PHEMA deposition.Öğe Mechanism Studies on CVD of Boron Carbide from a Gas Mixture of BCl3, CH4, and H-2 in a Dual Impinging-jet Reactor(WILEY-BLACKWELL, 2009) Karaman, Mustafa; Sezgi, Naime Ash; Dogu, Timur; Ozbelge, Hilmi OnderNearly pure boron carbide free from impurities was produced on a tungsten substrate in a dual impinging-jet chemical vapor deposition reactor from a BCl3, CH4, and H-2 mixture. The Fourier Tran form Infrared (FTIR) analysis proved the formation Of reaction intermediate BHCl2, which is proposed to occur mainly in the gaseous boundary layer next to the substrate surface. Among a large number of reaction mechanisms proposed only the ones considering the molecular adsorption of boron carbide on the substrate surface gave reasonable fits. In the proposed mechanism dichloroborane is formed in the gas phase only as a by-product. Boron carbide, on the other hand, is formed through a series of surface reactions involving adsorbed boron trichloride, adsorbed methane and gas phase hydrogen. The simultaneous fit of the experimental rate data to the model expressions gave correlation coefficient values of 0.977 and 0.948, in predicting the B4C and BHCl2 formation rates, respectively. (c) 2009 American Institute of Chemical Engineers AIChE J, 55: 701-709, 2009Öğe Photoelectrochemical Biosensing Approach for Alcohol Determination by "Wiring" of Alcohol Oxidase Photonically with P(SNS-NH2)/AOx/CNT/[Ru(bpy)(3)](2+) Modified Electrodes(TAYLOR & FRANCIS INC, 2014) Yildiz, H. B.; Kamaci, Musa; Karaman, Mustafa; Toppare, Levent; Sayin, SerkanA photoelectrochemical alcohol biosensor was designed through photonic wiring of alcohol oxidase (AOx) onto conducting polymer of 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)benzenamine (SNS-NH2) and carbon nanotubes (CNTs) modified gold slides. The photoelectrochemical biosensors utilize a photonically wired electrode that oxidizes primary alcohols to aldehydes. Three different alcohols namely methanol, ethanol, and n-propanol were used as the substrates. In the presence of different concentrations of primary alcohol, the photocurrents were obtained by irradiating of the photoelectrochemical cell containing P(SNS-NH2)/AOx/CNT/[Ru(bpy)(3)](2+) electrode as the anode under air. The bipyridine complex [Ru(bpy)(3)](2+) was used to activate photoinduced electron-transfer reaction and it acted as a redox mediator to activate the bioelectrocatalytic functions of AOx. Therefore, it was shown the photonic electron-transfer wiring of AOx with the electrode. Sensitivity experiments, optimum pH value, operational stabilization and shelf life of the photoelectrochemical biosensor were investigated. Finally, the photoelectrochemical biosensors were used for alcohol detection in real samples.Öğe A photoelectrochemical device for water splitting using oligoaniline-crosslinked [Ru(bpy)(2)(bpyCONHArNH(2))](+2) dye/IrO2 nanoparticle array on TiO2 photonic crystal modified electrode(PERGAMON-ELSEVIER SCIENCE LTD, 2016) Yildiz, Huseyin Bekir; Carbas, Buket Bezgin; Sonmezoglu, Savas; Karaman, Mustafa; Toppare, LeventThis article describes the construction of photoelectrochemical cell system splitting water into hydrogen and oxygen using UV-vis light under constant applied voltage. Oligoaniline-crosslinked 2-(4-aminobenzyl)malonic acid functionalized IrO2 center dot nH(2)O nanoparticles and visible light absorbing dye, [Ru(bpy)(2)(bpyCONHArNH(2))(+2)] arrays on titanium dioxide (TiO2) photonic crystals modified electrodes were used as photoanode, and nanostructures based on bonding of Pt nanoparticles by using electropolymerization on poly 4-(2,5-di(thiophene-2-il)-1H-pyrrol-1-il)benzenamine P(SNS-NH2) conducting polymer modified gold electrode acted as cathode. Each component in anode and cathode of the system was characterized successfully using the methods related. Some optimization studies such as the molar concentration ratio of [Ru(bpy)(2)(bpyCONHArNH(2))(+2)] dye to IrO2 center dot nH(2)O nanoparticles, the optimum cycle number of each components and thickness of TiO2 film were performed in order to investigate the system performance. Furthermore, the photocurrent generation capacity of the photoanode against oxygen resulting and UV stability experiments of photoanode were also investigated. After obtained all necessary informations and improvements of the system, the cell was constructed, and corresponding hydrogen gas evolution from water splitting was calculated as 1.25 x 10(-8) mol/cm(2) by using a gas chromatography (GC). The cell generated a photocurrent with a quantum yield of 3.5%. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Plasma Enhanced Chemical Vapor Deposition of Poly(2,2,3,4,4,4-hexafluorobutyl acrylate) Thin Films(WILEY-V C H VERLAG GMBH, 2015) Karaman, Mustafa; Yenice, EzgiThe synthesis of poly(2,2,3,4,4,4-hexafluorobutyl acrylate) (PHFBA) thin films using plasma enhanced chemical vapor deposition (PECVD) method is reported. PHFBA is a non-toxic and low surface energy polymer containing a-CF3 end group, which makes PHFBA a suitable hydrophobic finish. The effects of plasma power and substrate temperature on chemical and morphological structure of as-deposited films are studied. A greater retention of the perfluoroalkyl functionality is found for the depositions carried out at low powers and high temperatures. PHFBA thin films show superhydrophobic properties when deposited on rough fiber mat surfaces with observed water contact angles greater than 150 degrees.Öğe Preparation and characterization of polyvinyl borate/polyvinyl alcohol (PVB/PVA) blend nanofibers(WILEY-BLACKWELL, 2012) Koysuren, Ozcan; Karaman, Mustafa; Dinc, HavvaIn this study, it was aimed to prepare polyvinyl borate/polyvinyl alcohol blend nanofibers by electrospinning process. Polyvinyl borate was synthesized by the condensation reaction of polyvinyl alcohol and boric acid. Polyvinyl borate itself was not suitable for electrospinning process. To improve fiber formation capability, polyvinyl borate was blended with polyvinyl alcohol before electrospinning process. A series of nanofibers with various polyvinyl borate concentrations in polyvinyl alcohol were prepared. Homogeneous and highly porous mat containing 100-250 nm diameter nanofibers were obtained by electrospinning process. According to the FTIR results, boron atoms were found to be integrated into the polymer network. There is not any significant effect of polyvinyl borate content on fiber morphologies according to SEM images. The blend composition with the highest polyvinyl borate content was found to be suitable for thermally stable nanofiber formation according to the TGA results. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012Öğe Self-supporting superhydrophobic thin polymer sheets that mimic the nature's petal effect(ELSEVIER, 2012) Karaman, Mustafa; Cabuk, Nihat; Ozyurt, Demet; Koysuren, OzcanThe high adhesive force between the red rose petal and the water droplet on its surface is termed as the 'petal effect', which is caused by the hierarchical array of micro papilla on the surfaces together with the nano-folds existing on top of each papilla. Because of that special surface topography, the surface is superhydrophobic, but at the same time highly adherent to the water droplet such that the droplet cannot move even if the surface is turned upside down. In this work, we produced a thin (thickness below 1 mu m) self-supporting polymer sheet that mimics the surface of a red rose petal. The product is a two-layer polymer sheet made from poly(glycidyl methacrylate) (PGMA) as the supporting layer and a hydrophobic poly(1H, 1H, 2H, 2H-perfluorodecyl acrylate) (PPFDA) on top of it as the functional layer, both of which were deposited by initiated chemical vapor deposition (iCVD) process. The integration of conformal and solvent-free iCVD process into the classical two-step molding procedure allowed exact transfer of surface topography of the petal surface, which was verified by SEM analysis. The static contact angle of water droplet on the surface of the polymer replica was found to be 152 +/- 3 degrees, and the water droplet did not roll-off even the polymer sheet is tilted or turned upside down. (C) 2012 Elsevier B.V. All rights reserved.
