An atmospheric pressure oxygen and helium plasma was used to activate the surfaces of polyethylene (PE) and polymethyl methacrylate (PMMA). The plasma physics and chemistry was investigated by numerical modeling. It was shown that as the electron density of the plasma increased from 3x10¹⁰ to 1x10¹² cm^-3, the concentration of O atoms and metastable oxygen (¹∆_gO₂) molecules in the afterglow increased from 6x10¹⁵ to 1x10¹⁷ cm^-3, while the concentration of ozone decreased from 5x10¹⁵ to 2x10¹⁵ cm^-3. The oxygen atoms, metastable oxygen (¹∆_g O₂) molecules and ozone were the principle reactive species present in the afterglow. Exposing the polymers to the plasma afterglow for up to 30 seconds led to surface activation and an increase in bond strength of the polymers to adhesives by as much as 16 times. X-ray photoelectron spectroscopy of PMMA revealed an 8% increase in the C 1s peak area attributed to carboxylic acid groups (288.9 eV). In addition, the C 1s peak due to the methyl pendant groups (285.0 eV) decreased by 5%. The O:C ratio of PMMA increased from 0.4 to 0.7 after plasma treatment. Surface analysis of the polymers by internal reflection infrared spectroscopy confirmed the presence of carboxylic acid groups at 1710 cm^-1 and hydroxyl groups at 3100 to 3500 cm^-1 after activation. These results indicate that oxygen atoms and metastable O₂ molecules generated in the plasma rapidly oxidize the polymer chains. The experimental results as well as a detailed description of the reaction mechanism will be presented at the meeting.

A saddle-like ICP antenna with the several spiral coils distributed with an angular uniformity and enveloping a quartz tube of a plasma reactor was developed. It generates a transversal RF field directed normally to axis of this reactor. Due to such a design property of this antenna can be tuned between an initial capacitively coupled and a following inductively coupled state to facilitate a plasma ignition especialy at atmospheric pressure. Unlike a conventional coil generating a filament-like ICP atmospheric discharge this antenna provides a larger high temperature area for evaporation of precursor as well as for a plasma-chemical reaction. This antenna was successfully tested for nanocoating by silicon dioxide of the different surfaces including the inner walls of the hollow articles.

1. Y.Glukhoy, I. Ivanov RF Atmospheric Plasma Systems for Nanopowder Production and Deposition of Nanocrystallines. AVS 53rd International Symposium, San Francisco, California, November , 2006 CA, USA.