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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 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 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 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 Surface Treatments for Biological, Chemical, and Physical Applications Preface(WILEY-V C H VERLAG GMBH, 2017) Gursoy, Mehmet; Karaman, Mustafa[Abstract not Available]Öğe Surfaces in Nature(WILEY-V C H VERLAG GMBH, 2017) Gursoy, Mehmet; Karaman, Andmustafa[Abstract not Available]
