There are numerous features of electron beam-generated plasmas that distinguish them from discharges. In particular, most of the electron beam energy is spent on gas ionization (≈ 50 %), some on gas dissociation and very small amount on excitation. Thus, less radicals and photons are produced in electron beam-generated plasmas compared to discharges. Moreover, the electron temperature is low (< 1eV) so that the plasma potential is low and therefore the energy of the ions (1-5 eV) that attack the surface is low. These low ion energies minimize the undesirable physical sputtering and ion-assisted chemical etching of polymer surfaces, thereby limiting changes to the polymer surface morphology and the depth of modification. Despite these differences, the chemical structure of the polymer surface exposed to electron beam plasma is changed. In this work, we focus on understanding the mechanism of plasma induced polystyrene modification in nitrogen through a careful analysis of the functional groups formed and their distribution with depth.

 

This work was supported by the Office of Naval Research.