Yazar "Cansoy, C. Elif" seçeneğine göre listele

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    Applicability of Cassie-Baxter equation for superhydrophobic fluoropolymer silica composite films
    (Elsevier, 2015) Cengiz, Ugur; Cansoy, C. Elif
    In this study, surface topographies and wettabilities of flat and composite rough films of perfluoro-styrene (TM/S) random copolymers with silica particles were investigated. The water and oil repellencies of flat TM/S copolymer and rough silica-TM/S composite surfaces were studied with varying perfluoro and silica contents. Increase in silica content resulted in an increase in water contact angle values; water contact angle values increased from 113 up to 170, and the resultant surfaces were showing extremely superhydrophobic behavior depending on their silica contents. However a decrease in hexadecane contact angles from 61 to 25 depending on both silica %wt and perfluoro content of the TM/S copolymer was seen. Applicability of Cassie-Baxter equation was also investigated for TM/S copolymer films with silica particles. The results showed that Cassie-Baxter equation cannot be used for superhydrophobic surfaces, however, can be applied to oleophilic surfaces with caution. The oil repellencies of TM/S flat films in the terms of contact angle hysteresis was also compared with perfluoroethyl alkyl methacrylate-methyl methacrylate copolymer (TM/MMA) by using oil drops with varying surface tensions between 20.9 mN/m and 26.9 mN/m. The surface oleophobicities were changed according to the characteristics of the functional groups of MMA and S. The dependency of work of adhesion results of TM/S flat surfaces on wt.% of perfluoroalkyl content was also examined. (C) 2015 Elsevier B.V. All rights reserved.
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    The effect of pattern sizes on oleophobicity and superhydrophobicity of micropatterned surfaces
    (Elsevier Science Sa, 2016) Cengiz, Ugur; Cansoy, C. Elif
    In this study, cylindrical pillars with varying diameters between 10 mu m to 100 mu m, seperation distances between 5 mu m to 10 mu m, constant heights of 40 mu m +/- 2 and solid area fractions [f(s)(CB) (geo)] between 0.349 to 0.712 were prepared by deep reactive ion etching process and all surfaces were hydropho-bized/oleophobized by coating with perfluoro-styrene (TM/S) random copolymer that was synthesized in CO2-expanded monomer. It was found that, oleophobic behaviors of the patterned surfaces were affected from the type of the hydrocarbon liquids used and with the increase of hydrocarbon liquid chain lengths cylindrical pillar surfaces exhibited more oleophobic behavior. Pattern sizes also affected both oil and water drop CA values however oil and water drops behaved oppositely on the pillar surfaces. Applicability of Cassie-Baxter equation on cylindrical pillar surfaces was also investigated and was found that CA values of both water and hydrocarbon liquids were not obeying Cassie-Baxter theory however in the case of hydrocarbon liquids deviations from the theory were much more larger. (C) 2016 Elsevier B.V. All rights reserved.
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    Öğe
    The effect of perfluoroalkyl and hydrocarbon liquid chain lengths on oleophobic behaviors of copolymer surfaces
    (Elsevier Science Bv, 2014) Cansoy, C. Elif; Cengiz, Ugur
    In this work, the effect of wt.% of perfluoroalkyl content and also hydrocarbon chain length on oleophobic properties of perfluoroethyl alkyl methacrylate-methyl methacrylate (Zonyl-TM-MMA) copolymers was investigated. The wetting performance of p(Zonyl-TM-ran-MMA) copolymer films by hydrocarbon liquids was found to be strongly depended on perfluoroalkyl chain lengths. Besides, increase in hydrocarbon chain length also caused an increase in contact angle results of p(Zonyl-TM-ran-MMA) copolymer films due to the stronger cohesion interactions of liquid molecules and this resulted in weaker adhesion interactions between copolymer surface and hydrocarbon drop. It was also discovered that contact angle hysteresis, Delta cos theta, values of copolymers depend on both wt.% Zonyl-TM content and also hydrocarbon chain length of liquids. (C) 2013 Elsevier B.V. All rights reserved.