Oxygen dependent plasma–particle-interaction

The etching process of single polymer particles is investigated using a noninvasive in situ light scattering technique, based on two different wavelengths. A systematic variation of admixed oxygen to an argon discharge allows us to investigate and model the basic etching processes and connect the experimentally available size evolution with surface properties and processes. The comparison of particles with different materials allows us to differentiate between the influence of the discharge itself and the material-specific aspects of the particles. The same reaction mechanism of ion-assisted surface reactions fits both investigated particle species, melamine formaldehyde (MF) and polymethyl-methacrylate (PMMA). The etching rates of PMMA were four times larger than in the case of MF under the same discharge conditions and match the stronger surface modification of PMMA particles, highlighting the possibility of the presented setup to systematically study plasma–particle and thus plasma–surface interactions.