Insights in Molecular Structure of Organosilicon Plasma Polymer Produced by Means of Atmospheric Pressure Dielectric Barrier Discharge Process

摘要

Most of polymers resulting from plasma polymerization exhibit a structure, which is very complex and different from those synthesized by conventional polymerization methods. The molecular structure of such plasma polymers is difficult to assess, but its characterization is a crucial issue. Mass spectrometry (MS) seems to be a promising analytical approach to get this molecular information. The chemical structure of a ppHMDSO (plasma polymer HexaMethyl-DiSiloxane) film, deposited by means of atmospheric pressure dielectric barrier discharge process, has first been characterized by means of FTIR spectroscopy. Additional insights in thernpolymer structure were provided by mass spectrometric techniques. MALDI-TOF-MS and ESI-0-TOF-MS analyses were carried out to obtain information on high molecular weight oligomers and/or small polymers collected in the THF soluble fraction of a ppHMDSO film. Although uncertainty still remains about the detected species, it could be concluded they were copolymers such as poly(dimethylsiloxane-co-methylsiloxane) or poly(dimethylsiloxane-co-SiO_2) with a number of monomers up to 20, and some structures could be proposed for the end groups.