Surface characterization and radical decay studies of oxygen plasma-treated PMMA films

Authors

  • Ozge Ozgen,

    1. Department of Polymer Science and Technology, Middle East Technical University, Ankara, Turkey
    2. Department of Physics, Faculty of Engineering, Atılım University, Ankara, Turkey
    Search for more papers by this author
  • Eda Ayse Aksoy,

    1. Central Laboratory, Middle East Technical University, Ankara, Turkey
    2. METU-BIOMATEN Center of Excellence in Biomaterials and Tissue Engineering, Ankara, Turkey
    Search for more papers by this author
  • Vasif Hasirci,

    1. Department of Polymer Science and Technology, Middle East Technical University, Ankara, Turkey
    2. METU-BIOMATEN Center of Excellence in Biomaterials and Tissue Engineering, Ankara, Turkey
    3. Department of Biological Sciences, Middle East Technical University, Ankara, Turkey
    4. Department of Biotechnology, Middle East Technical University, Ankara, Turkey
    Search for more papers by this author
  • Nesrin Hasirci

    Corresponding author
    1. Department of Polymer Science and Technology, Middle East Technical University, Ankara, Turkey
    2. METU-BIOMATEN Center of Excellence in Biomaterials and Tissue Engineering, Ankara, Turkey
    3. Department of Biotechnology, Middle East Technical University, Ankara, Turkey
    • Department of Chemistry, Middle East Technical University, Ankara, Turkey
    Search for more papers by this author

Correspondence to: Nesrin Hasirci, Department of Chemistry, Middle East Technical University, Ankara 06800, Turkey.

E-mail: nhasirci@metu.edu.tr

Abstract

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° to 26°. 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 ~2 nm 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 © 2012 John Wiley & Sons, Ltd.

Ancillary