Remote Atmospheric Pressure Plasma Activation of Polymers
Eleazar Gonzalez II1, Michael Barankin1, Peter C. Guschl2, and Robert F. Hicks1. (1) Chemical & Biomolecular Engineering, University of California, Los Angeles, Box 951592, Los Angeles, CA 90095-1592, (2) Surfx Technologies, Culver City, CA 90232
The surfaces of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyphenylene sulfide (PPS) were activated remotely using an atmospheric pressure oxygen and helium plasma. The afterglow of the plasma, containing O atoms, and to a lesser extent metastable oxygen (1Dg O2) and ozone, came into contact with the polymer surface for periods of time ranging from 0 to 400 milliseconds. Changes in the surface energy and chemical composition of the surfaces were determined by contact angle measurements and x-ray photoelectron spectroscopy (XPS). The decrease in water contact angle followed an exponential decay indicative of a Langmuir adsorption process. For both PET and PEN, x-ray photoelectron spectroscopy revealed an 18 to 29% decrease in the area of the C 1s peak located at 285 eV, which is attributable to the aromatic carbons. The C 1s peak area corresponding to the C=O increased by 11.4 and 23.6% for PET and PEN, respectively, while the C 1s peak area resulting from the C-O bond increased by approximately 5% for both polymers. These results demonstrate that the O atom radicals generated in the remote plasma oxidize the aromatic rings in the polymer chain. The reaction is believed to occur by H abstraction from the polymer surface by the O radical, followed by O2 addition to the resulting aromatic radical. The peroxy species then decomposes to from ketones and alcohols. The surface of PPS was also oxidized, despite not containing any ethylene carbons as found in PET and PEN. It is believed that the O radicals attack the aromatic rings and abstract a hydrogen atom, which has not been seen before in literature. The results of this study will be presented at this meeting.