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 charged and neutral particles were determined. A wide variety of polymeric materials were then exposed to a thermal atomic oxygen environment at fluxes of 10{sup 22} atoms/m{sup 2}-sec. Bulk material temperatures were maintained at 10, 45, and 75{degrees}C during exposure. Mass loss rate of polymers was primarily controlled by the atomic oxygen species which nonetheless constituted only one percent or less of the total plasma chamber pressure. Ions and electrons which were determined to be minor constituents of the plasma did not contribute to the mass loss. Sputtering by the thermal oxygen atom had essentially no influence in the removal of surface atoms of polymers. Mass loss of polymers under atomic oxygen exposure was confirmed to be a thermally activated process with activation energies in the range from 1 to 48 kJ/mole. Polymer reactions with atomic oxygen may be described by a two-step process of atomic oxygen diffusion into the polymer surface with subsequent reactions with bonds to generate low molecular weight gases. 42 refs., 9more » figs., 8 tabs.« less