OXYGEN PLASMA ENVIRONMENT - ITS EFFECT ON POLYMERS

The response of polymers to atomic oxygen in a radio frequency plasma was investigated. As a first step, an effort was made to characterize the nature of an oxygen plasma. Relative concentrations of various cha rged and neutral particles were determined. A wide variety of polymeri c materials were then exposed to a thermal atomic oxygen environment a t fluxes of 10(22) atoms/m2-sec. Bulk material temperatures were maint ained at 10, 45, and 75-degrees-C during exposure. Mass loss rate of p olymers was primarily controlled by the atomic oxygen species which no netheless constituted only one percent or less of the total plasma cha mber pressure. Ions and electrons which were determined to be minor co nstituents of the plasma did not contribute to the mass loss. Sputteri ng by the thermal oxygen atom had essentially no influence in the remo val of surface atoms of polymers. Mass loss of polymers under atomic o xygen exposure was confirmed to be a thermally activated process with activation energies in the range from 1 to 48 kJ/mole. Polymer reactio ns with atomic oxygen may be described by a two-step process of atomic oxygen diffusion into the polymer surface with subsequent reactions w ith bonds to generate low molecular weight gases.