Surface modification of polyethylene by Ag+ and Au+ ion implantation observed by phase imaging atomic force microscopy

High density polyethylene (HDPE) has been modified by Ag+ and Au+ ion implantation with the energy of 60 and 200 keV, respectively. The doses of implanted silver and gold ions were as follows: 1 × 1015, 5 × 1015 and 1 × 1016 ions/cm2. The surface topography was observed using atomic force microscopy (AFM), while the surface composition changes were detected using phase imaging AFM. Phase analysis of AFM images shows that both physical and chemical changes occur on the surface of HDPE and that these changes depend on the nature of implanted ions and on the implantation dose. Silver ion implantation causes a higher degree of chemical changes, while the implantation of gold ions causes a higher degree of physical changes. Breakpoints were observed for the implantation doses of 0.6 × 1015 and 4.4 × 1015 ions/cm2 for silver and gold ions, respectively. Physical changes are confirmed by the analysis of mean square roughness and power spectral density slopes as functions of the implantation dose. The position and half-width of peaks in histograms of phase AFM images confirmed the changes in surface composition.