Surface chemistry and wettability of plasma-treated PTFE

Polytetrafluoroethylene sheet samples have been treated in a low-power plas ma cell using O-2, Ar, N-2 and NH3 feed gases, The surfaces became signific antly more wettable in simulated body fluid and bromonaphthalene, By using a range of techniques, this was found to be principally due to chemical cha nges at the surface induced by the plasma treatments. Static SIMS and XPS s howed that these changes were defluorination and incorporation of unsaturat ed hydrocarbons and oxygen-containing moieties, The extent of these changes depended on the feed gas used, being least for O-2 and greatest for Ar. In addition, it was found that surfaces became activated by the plasma treatm ents and continued to change chemically during subsequent storage in simula ted body fluid. By contrast, storage in air resulted in partial recovery to wards the untreated surface state, which was attributed to relaxation proce sses in the modified layer. Copyright (C) 2000 John Wiley & Sons, Ltd.