Introduction of sulfate groups on poly(ethylene) surfaces by argon plasma immobilization of sodium alkyl sulfates

Sulfate groups were introduced at the surface of poly(ethylene) (PE) samples. This was accomplished by immobilizing a precoated layer of either sodium 10-undecene sulfate (S11(:)) or sodium dodecane sulfate (SDS) on the polymeric surface by means of an argon plasma treatment. For this purpose, S11(:) was synthesized by sulfating 10-undecene-1-ol using the pyridine-SO3 complex. The presence of sulfate groups at the polymeric surfaces was confirmed by X-ray Photoelectron Spectroscopy (XPS). The presence of an unsaturated bond in the alkyl chain of the surfactant improved the efficiency of the immobilization process. About 25% of the initial amount of sulfate groups in the precoated S11(:) layer was retained at the PE surface compared to only 6% for SDS. The maximum surface density of sulfate groups on the resulting samples was one group per 45 and 127 Å2 respectively.