Surface recovery and degradation of air dielectric barrier discharge processed poly(methyl methacrylate) and poly(ether ether ketone) films

Non-aromatic [poly(methyl methacrylate), PMMA] and aromatic [poly(ether ether ketone), PEEK] polymers containing carbonyl groups in their structure have been modified in an air dielectric barrier discharge (DBD). Hydrophilic property governed by further oxygenation of the polymer surface was demonstrated by contact angle measurements and corresponding XPS derived O/C ratios. The modified polymer films stored for a month revealed recovery of such modification by the restoration of the contact angles and O/C ratios to their original values. A post-processing XPS investigation of the aged films revealed degradation and loss of structurally related functional groups from both the polymer surfaces. The loss of oxygenated functionality incorporated by DBD processing of PMMA was observed from the corresponding SIMS data.