Plasma Parameter Aspects in the Fabrication of Stable Amine Functionalized Plasma Polymer Films

Amine containing plasma polymer films are of interest due to their ability to bind biomolecules either covalently or electrostatically. One issue with generating such plasma polymers is the need to generate sufficient amine density on the surface to enable binding, while simultaneously maintaining the chemical, physical stability of the surface in aqueous media. Here we investigate the relationship between plasma parameters, film stability for two commonly used monomers, allylamine AA, ethylenediamine EDA. Plasma polymer films from AA, EDA were produced at radio frequency RF powers between 2 and 20 W at a constant monomer flowrate. Deposition rate, ion flux, ion energy, plasma phase mass spectrometry were used to investigate the plasma-surface interactions. Film stability was assessed by comparing X-ray photoelectron spectroscopy XPS, atomic force microscopy AFM measurements before, after washing in phosphate buffered saline PBS. The results show that films generated from EDA plasmas are generally unstable in aqueous media, while films generated from AA plasmas exhibit higher stability, particularly those deposited at high RF power. The chemical, physical stability of the films is then related to the mechanisms of deposition, the energy density provided to the surface during film growth.