Atmospheric pressure plasma polymerization of organics: effect of the presence and position of double bonds on polymerization mechanisms, plasma stability and coating chemistry

Highlights: • Double bonds in organic precursors modify the electrical behaviour of an atmospheric DBD • Double bonds in organic precursor induce a specific polymerization pathway in the plasma phase • A specific fragment for polymerization is evidenced when double bonds are present • The position of the double bond is of crucial importance in the preservation of the precursor chemistry -- Abstract: Oxygen rich organic coatings are synthesized in a dielectric barrier discharge at atmospheric pressure. The critical effect of the precursor structure on the final chemical and physical properties of the synthesized coatings and the plasma characteristics are reported. A correlation is proposed between the electrical, optical emission spectroscopy and atmospheric mass spectrometry (MS) measurements of the plasma phase with the chemical properties of the synthesized films. It is shown that the addition of a precursor in an argon plasma leads to a stabilization of the discharge, critically dependent on the precursor structure itself. Different polymerization pathways are evidenced for the saturated and unsaturated precursors by the monitoring of some specific fragments by MS. The polymerized coatings are also characterized with X-Ray Photoelectron Spectroscopy, Infrared Spectroscopy and Atomic Force Microscopy. The presented results not only evidence a stronger preservation of the precursor structure with double bonds in the plasma phase but also reveal the essential role of the distance separating the unsaturation and a function of interest.