Surface modification of polytetrafluoroethylene by nitrogen ion implantation

Polytetrafluoroethylene (PTFE) was implanted in vacuum by N ions. The influence of experimental parameters was studied by varying ion energy from 2 to 20 keV with the same fluence of 1.4×1017 ions/cm2. The ion energy strongly affected the surface composition, microstructure, and wettability of PTFE. Five chemical bonds, CF3, CF2, CF, C–O, and elemental carbon bonds, were observed on the surface of all the as-implanted samples. The content of the various chemical bonds changed with increasing ion energy. The content of elemental carbon bond reached a maximum value of 45.81% on the surface of the sample implanted with ion energy of 5 keV. Displacement of the binding energies of the C 1s peak components was observed on the surfaces of samples implanted with ion energies equal to or greater than 5 keV. Numerous microfibers drawn up in the same orientation were observed on the ion-irradiated surfaces. The droplet contact angle of the as-implanted samples increased gradually with increasing ion energy, and reached a maximum value of 117.4° on the surface of the sample implanted with ion energy of 20 keV.