Effect of electric charge accumulation on the surface properties of PS samples irradiated with low energy ions

Low energy ion irradiation produces an accumulation of electric charge on insulator surfaces that influences the surface properties of irradiated samples. This phenomenon can be used as a complementary tool to improve the efficacy of polymer surface treatment. Samples of polystyrene (PS) have been implanted with 2.2 keV D2+ ions to a fluence of 3.9 × 1016 D/cm2 with and without the use of a charge neutralization system. The physical and physicochemical properties of the surface were characterized by elastic recoil detection (ERD-ExB), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). AFM characterization shows that the surface roughness either decreases or increases after ion beam bombardment with or without surface neutralization, respectively. The wettability of treated surfaces, which increases with both methods of implantation, is enhanced by the charge accumulation on the surface. XPS characterization revealed the formation of C–O, CO and O–CO molecular bonds with both treatments and the oxygen adsorption is increased in samples implanted without neutralization. The level of surface charging affects the chemical composition and the roughness of the surface. Thus, it gives a complementary tool to adjust the wettability and other surface properties of PS.