WETTABILITY IMPROVEMENT OF PMMA FILMS WITH HIGH FREQUENCY RF PLASMAS

Poly(methyl methacrylate) (PMMA) has a wide variety of applications due to its attractive physical and optical properties. Due to its hydrophobic (water-repellent) character, the surface of PMMA should be modified before being used in applications. In this study, the surface of PMMA films were modified by 40.68 MHz high frequency CCP (capacitive-coupled plasma) RF system with nitrogen (N) and argon (Ar) gases. The experiments carried out under various plasma powers while the pressure and treatment time were kept constant. The wettability of the plasma treated surfaces was analyzed with contact angle and surface free energy (SFE) measurements. Also, the change in the chemical structure of the surfaces was investigated with X-ray photoelectron spectroscopy (XPS). The results showed that all plasma treatments enhanced the hydrophilicity of the surfaces and the lowest contact angle values obtained at high plasma power. The total SFE of the treated surfaces increased with power and the main contribution to total SFE came from polar components. The polar groups formation on the surface after plasma treatment was proved with XPS results. Hence, it was found that high frequency CCP RF plasmas can be used effectively to obtain hydrophilic polymer surfaces.