Effects of Ar- and Ar/O₂-plasma-treated amorphous and crystalline polymer surfaces revealed by ToF-SIMS and principal component analysis

The effects of argon (Ar) and a mixture of Ar and oxgyen(Ar/O₂) plasmas on amorphous and semi-crystalline poly(bisphenol A hexane ether) thin films were investigated by time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and principal component analysis (PCA). PCA results of the ToF-SIMS spectra indicate that an Ar/O₂ plasma produced less physical sputtering and had a higher chemical reactivity than did an Ar plasma, regardless of whether an amorphous or a crystalline surface was involved. However, the chemical differences between the Ar- and Ar/O₂-plasma- treated semi-crystalline films were much smaller. The observed results can be explained by the higher resistance of the polymer crystalline regions to physical sputtering and chemical etching.