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    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, Demet
    Noncovalent 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., 2013
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    Electrospun Nanofibers with CdTe QDs, CdTeSe QDs and CdTe/CdS Core-shell QDs
    (IEEE, 2017) Baslak, Canan; Koysuren, Ozcan; Kus, Mahmut
    [Abstract not Available]
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    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, Havva
    The 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.
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    Preparation and characterization of polyvinyl alcohol/carbon nanotube (PVA/CNT) conductive nanofibers
    (WALTER DE GRUYTER GMBH, 2012) Koysuren, Ozcan
    The aim of this study was to prepare polyvinyl alcohol/carbon nanotube (PVA/CNT) conductive nanofibers by the electrospinning process. Prior to composite preparation, carbon nanotubes are dispersed homogeneously in N-methyl-2-pyrrolidone (NMP) and mixed with a PVA solution. A series of PVA/CNT films and nanofibers with various CNT compositions are prepared. Electrical conductivity and specific capacitance of spin-coated PVA/CNT films and electrospun PVA/CNT fibers increase with an increase in CNT content. Electrospun PVA/CNT nanofibers with a larger electrode surface result in a higher specific capacitance when compared with spin-coated PVA/CNT films. According to the morphology analysis, homogeneous and highly porous PVA/CNT mats containing 50-300 nm diameter nanofibers are obtained by the electrospinning process.
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    Preparation and characterization of polyvinyl borate/polyvinyl alcohol (PVB/PVA) blend nanofibers
    (WILEY-BLACKWELL, 2012) Koysuren, Ozcan; Karaman, Mustafa; Dinc, Havva
    In 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, 2012
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    Self-supporting superhydrophobic thin polymer sheets that mimic the nature's petal effect
    (ELSEVIER, 2012) Karaman, Mustafa; Cabuk, Nihat; Ozyurt, Demet; Koysuren, Ozcan
    The 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.
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    Template assisted synthesis of photocatalytic titanium dioxide nanotubes by hot filament chemical vapor deposition method
    (ELSEVIER SCIENCE BV, 2013) Karaman, Mustafa; Sariipek, Fatma; Koysuren, Ozcan; Yildiz, H. Bekir
    Titanium dioxide thin films were deposited conformally over electrospun polymethyl methacrylate (PMMA) fibers by hot filament chemical vapor deposition method. Deposition rates were observed to be very high to allow for rapid coatings. Thermal annealing of as deposited materials leads the clean decomposition of the polymeric inner layer and formation of randomly distributed anatase TiO2 nanotubes. Nanotubular TiO2 structure was clearly identified by SEM and that structure is ideal for good photocatalytic activity because of its high surface area per unit volume ratio. FTIR and XPS results show the formation of stoichiometric TiO2, and the crystalline form of the final nanotubes was found to be anatase (1 0 1) after XRD analysis. High photocatalytic activity of TiO2 nanotubes under UV irradiation was observed with an apparent rate constant of 0.74 h(-1) for methyl orange decomposition. (C) 2013 Elsevier B.V. All rights reserved.