Browsing by Author "Ozgen, Ozge"

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Citation - WoS: 6
Citation - Scopus: 6
Modification of Poly(methyl Methacrylate) Surfaces With Oxygen, Nitrogen and Argon Plasma
(Amer Scientific Publishers, 2014) Ozgen, Ozge; Özgen, Özge; Hasirci, Nesrin; Özgen, Özge; Physics Group; Physics Group; 06. School Of Engineering; 01. Atılım University
Poly(methyl methacrylate) (PMMA) is a strong and lightweight material used in wide range of areas changing from lenses to medical and dental devices. In this study, PMMA samples were modified by oxygen, nitrogen and argon plasma with application of 100 watts 13.56 MHz radio frequency (RF) discharge for different periods (5 min, 15 min and 30 min) and the effects of plasma parameters on surface chemistry, hydrophilicity, surface free energy and topography were examined. XPS analysis showed formation of free carbonyl and carbonate groups by oxygen plasma, carboxylic acid and free carbonyl by argon plasma, and imine, primary amine, amide and nitrozo functional groups by nitrogen plasma treatments. For all cases plasma treatment created more hydrophilic surfaces with lower water contact angles than that of pristine PMMA. Also, plasma caused an increase in the surface free energy and its' polar components determined by Geometric Mean, Harmonic Mean, and Acid-Base approaches. AFM results showed increasing roughness parallel to the duration of plasma. As a result, each plasma treatment caused different functionalities and physical topographies on PMMA surfaces and different functionalities can be used for further developments such as binding specific active molecules to design biosensors or medical devices.
Citation - WoS: 40
Citation - Scopus: 44
Surface Characterization and Radical Decay Studies of Oxygen Plasma-Treated Pmma Films
(Wiley, 2013) Ozgen, Ozge; Aksoy, Eda Ayse; Hasirci, Vasif; Hasirci, Nesrin; Physics Group; 06. School Of Engineering; 01. Atılım University
Polymethylmethacrylate (PMMA) films were modified by RF oxygen plasma with various powers applied for different periods, and the effects of these parameters on the surface properties such as hydrophilicity, surface free energy (SFE), chemistry, and topography were investigated by water contact angle, goniometer, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy, and the types of the created free radicals and their decay were detected by electron spin resonance spectroscopy (ESR). SFE and contact angle results varied depending on the plasma parameters. Oxygen plasma treatment (100 W-30 min) enhanced the hydrophilicity of PMMA surface as shown by decreasing the water contact angle from 70 degrees to 26 degrees. XPS analysis showed the change in the amounts of the present functionalities as well as formation of new groups as free carbonyl and carbonate groups. The roughness of the surface increased considerably from similar to 2 nm to similar to 75 nm after 100 W-30 min oxygen plasma treatment. ESR analysis indicated the introduction of peroxy radicals by oxygen plasma treatment, and the intensity of the radicals increased with increasing the applied power. Significant decrease in radical concentration was observed especially for the samples treated with higher powers when the samples were kept under the atmospheric conditions. As a conclusion, RF plasma, causes changes in the chemical and physical properties of the materials depending on the applied parameters, and can be used for the creation of specific groups or radicals to link or immobilize active molecules onto the surface of a material. Copyright (C) 2012 John Wiley & Sons, Ltd.
Citation - WoS: 12
Surface Modification of Polymeric Biomaterials
(Blackwell Science Publ, 2013) Guney, Aysun; Kara, Filiz; Ozgen, Ozge; Aksoy, Eda Ayse; Hasirci, Vasif; Hasirci, Nesrin; Department of Psychology; Physics Group; 02. School of Arts and Sciences; 06. School Of Engineering; 01. Atılım University
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