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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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    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.