AVS 47th International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS1-ThA

Paper PS1-ThA1
Plasma Surface Modification of PET and Acrylic Coating Surfaces

Thursday, October 5, 2000, 2:00 pm, Room 310

Session: Plasma-Surface Interactions II
Presenter: M.K. Shi, Pacific Northwest National Laboratory
Authors: M.K. Shi, Pacific Northwest National Laboratory
A. Tyryshkin, Princeton University
G.C. Dunham, Pacific Northwest National Laboratory
M. Bowman, Pacific Northwest National Laboratory
G.L. Graff, Pacific Northwest National Laboratory
P.M. Martin, Pacific Northwest National Laboratory
G.J. Exarhos, Pacific Northwest National Laboratory
Correspondent: Click to Email
Plasma treatment has proven to be very effective in modifying polymer surface properties for enhanced surface compatibility and adhesion. The treatment is performed in vacuum and the effect can be achieved within a few seconds. These characteristics make plasma technology extremely appealing for the adhesion promotion of polymer-metal multilayer stacks that can be deposited inline and at high speed in a vacuum web-coater. The surface modification of poly(ethylene-terephthalate) (PET) and UV-cured tripropyleneglycol diacrylate films induced by remote N@sub2@ and Ar microwave (2.45 GHz) plasmas was investigated in order to better understand the plasma/surface interaction mechanisms. In-situ XPS analysis revealed that N@sub2@ and Ar plasma treatments led to removal, in entirety, of the initial oxygen-containing groups on the polymer surfaces. The removal of ester groups was much faster for the acrylic than for the PET, and the removal of ether groups was much faster than that of ester groups within the acrylic film. Electron parametric resonance (EPR) measurements indicated the presence of several types of free radicals. The concentration of these radicals was higher for N@sub2@ than for Ar plasma treatment and for the acrylic than for the PET film, which correlated well with the more pronounced surface modifications measured by XPS. Pulsed EPR measurements suggested that these radicals existed mainly in radical pairs and were distributed within 2000 Å from the top surface. The concentration of free radicals correlated well with the amount of N incorporated into the surface by N@sub2@ plasma treatment. These results strongly supported a free radical-dominated plasma/surface interaction mechanism and highlighted the important role of plasma UV emission. Water contact angle measurements indicated that the incorporated N atoms were responsible for the improved surface wettability.