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Gas-phase radicals are critical to many plasma processes involving polymers, including plasma polymerization and plasma modification of polymers. For example, nitrogen-containing discharges and H2O-vapor plasmas have been widely studied because of their ability to improve adhesion between polymers and a variety of substrates and to create wettable surfaces. To clarify mechanistic details, it is necessary to understand the chemical reactions that result when radicals impinge on surfaces during plasma processing. Understanding surface interactions of plasma species provides critical molecular level information about plasma processing. We have explored the gas-phase, the modified surface and the gas-surface interface for a variety of polymer surface modification processes. In addition to gas-phase and surface analytical data, data from our unique laser-based imaging of radicals interacting with surfaces (IRIS) technique will be presented. examines interactions of radicals during plasma processing. IRIS data for species in plasma polymerization and plasma modification systems will be presented. Results for plasma modification of several different polymers and polymeric membranes will be covered extensively. The interactions of different species are dependent on the polymer being modified, the plasma conditions, and ion bombardment. Additionally, data on the energetics of these radicals, analysis of the gas-phase species (via both mass spectrometry and optical emission spectroscopy), and mechanistic implications for plasma processing of polymers will be presented. Applications of these processes to biological molecule interactions will also be presented along with microfluidic chip modifications. Specifically, we will present results from protein fouling experiments and cell-surface interaction data. Collectively, these data show the importance of understanding the underlying chemistry in plasma processing of polymers. |