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Chemical and Morphological Characterization of Ultra‐Thin Fluorocarbon Plasma‐Polymer Deposition on 316 Stainless Steel Substrates: A First Step Toward the Improvement of the Long‐Term Safety of Coated‐Stents
Author(s) -
Haïdopoulos Marie,
Turgeon Stéphane,
Laroche Gaétan,
Mantovani Diego
Publication year - 2005
Publication title -
plasma processes and polymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 74
eISSN - 1612-8869
pISSN - 1612-8850
DOI - 10.1002/ppap.200400066
Subject(s) - materials science , fluoropolymer , x ray photoelectron spectroscopy , thin film , chemical engineering , polymer , contact angle , coating , fluorocarbon , nanotechnology , composite material , engineering
Summary: Metallic intravascular stents are medical devices used to scaffold a biological lumen, most often diseased arteries, after balloon angioplasty. They are commonly made of 316L stainless steel or Nitinol, two alloys containing nickel and chromium, which are classified as potentially toxic and carcinogenic by the International Agency for Research on Cancer. Their long‐term safety is therefore controversial, since the corrosion processes may lead to the release of several metallic compounds potentially toxic. Therefore, the strategy behind this work was to develop a process aiming the complete isolation of the devices from the body fluids by a thin, cohesive and strongly adherent coating of a plasma‐polymerized fluoropolymer. Ultra thin fluorocarbon films were deposited on pre‐treated stainless steel surfaces by radio frequency glow discharge plasma. Chemical composition, structure, hydrophobicity and morphology of the plasma‐polymer films were investigated by X‐ray photoelectron spectroscopy, Fourier‐transform infrared spectroscopy, water contact angle measurements and atomic force microscopy. Results show that the films were partially hydrogenated, amorphous, highly hydrophobic, smooth and pinhole‐free. Deposition on as‐received substrates however leads to partially hydrogenated, porous fluorocarbon coatings that consisted of heterogeneously distributed nanospherical particles. Thus, careful pre‐treatment prior to deposition proved essential, as demonstrated by its strong influence on the chemical composition of the interface, as well as the chemical structure and the morphology of the plasma‐polymer films. Finally, plasma‐polymer films were validated with respect to impermeability in a medium reproducing the physiological conditions that prevail in coronary arteries.