Insights in molecular structure of plasma-polymers deposited by means of Atmospheric Pressure Dielectric Barrier Discharge

摘要

Contrary to conventional polymerization techniques, plasma-polymerization leads to thin, poorly soluble and highly cross-linked films, with huge potential for industrial applications. Their microstructure - affected by plasma process parameters and the nature of the precursors - is thus quite difficult to assess, in particular when using traditional analytical tools such as infrared spectroscopy or solid-state NMR. In contrast, detailed structural features could be obtained from MS/MS experiments performed on intact oligomer adducts. In this study, plasma-polymerized films deposited by means of Atmospheric Pressure plasma generated by Dielectric Barrier Discharge (AP-DBD) were synthesized from the D4 cyclic siloxane precursor (octamethylcyclotetrasiloxane). Soluble parts of these samples were electrosprayed and mass-analyzed using a time-of-flight mass analyzer, allowing accurate mass measurements of polymer adducts in MS and of their product ions generated upon CID in MS/MS. Some new molecular architectures were then proposed for the main species as well as new activation processes found to occur within the plasma reactor.