Sulfonated Surfaces by Sulfur Dioxide Plasma Surface Treatment of Plasma Polymer Films

The preparation of thin film coatings with sulfonate and sulfate groups by plasma techniques is not straightforward due to limited volatility of suitable process vapours. We report a combination of plasma polymerisation and plasma treatment, treating heptylamine (HA‐SO2) and 1,7‐octadiene (OD‐SO2) plasma polymers with sulfur dioxide plasma. HA‐SO2 and OD‐SO2 plasma polymer surfaces exhibited different compositions with the latter showing almost twice the amount of sulfur, as well as polysulfonate. Ageing of HA‐SO2 plasma polymer surfaces in air or saline solution led to the disappearance of oligomers containing sulfonate and sulfate. Angle‐dependent XPS analysis of HA‐SO2 plasma polymers suggested that sulfur containing groups reptated into the plasma polymer upon storage after preparation. Various biological interactions occur on sulfated surfaces in biological systems. This paper adopted a combinatory approach of octadiene and aminated plasma polymers which were subsequently subjected to sulfur dioxide plasma treatment to overcome various problems associated with non‐plasma techniques. Surface studies revealed that the type of plasma polymers and ageing conditions play a role in the final chemical properties.