Characterization of sulfate and phosphate containing plasma polymer surfaces

This paper describes three methods for producing sulfated and phosphated surfaces using plasma-based technologies, namely plasma treatment, plasma polymerization, and plasma activation followed by chemical grafting. Plasma treatment using sulfur dioxide (SO₂) produced sulfur-containing groups while plasma polymerization using triisopropyl phosphite (TIP) as the monomer created phosphated surfaces. The plasma-plus-grafting technique involved deposition of an amine plasma polymer followed by grafting with vinyl sulfonate or vinyl phosphonic acid via Michael addition. The various oxidation states and surface charges of chemical groups present on the surfaces were assessed by the surface analytical techniques X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR). The stability and ageing mechanism of these plasma surfaces were also characterized.