Molecular Surface Analysis and Depth-Profiling of Polyethylene Modified by an Atmospheric Ar-D2O Post-Discharge

The injection of water vapor into ambient "open air" plasmas for the treatment of polymers represents a promising functionalization route for industrial and medical applications. The present study reports a scientist-independent methodology, based on the ToF-SIMS (time-of-flight secondary ion mass spectrometry) technique coupled with PCA/Wavelet-PCA (principal component analysis), to probe the (sub) surface chemical/structural modifications induced by an atmospheric Ar-D2O post-discharge on low density polyethylene (LDPE) films as a function of two external plasma parameters, namely sample-torch distance and treatment time. The SIMS characterization identifies two different families of samples (type I and II) as a function of time and distance. The highest reactivity of the D2O vapors with the LDPE films is achieved for times of few tens of seconds at a distance of 5mm from the plasma source.