title: X-ray photoelectron emission microscopy and time-of-flight secondary ion mass spectrometry analysis of ultrathin fluoropolymer coatings for stent applications.
abstract: Fluoropolymer plasma coatings have been investigated for application as stent coatings due to their chemical stability, conformability, and hydrophobic properties. The challenge resides in the capacity for these coatings to remain adherent, stable, and cohesive after the in vivo stent expansion, which can generate local plastic deformation of up to 25%. Plasma-coated samples have been prepared by a multistep process on 316L stainless steel substrates, and some coated samples were plastically deformed to mimic a stent expansion. Analyses were then performed by X-ray photoelectron spectroscopy (XPS), X-ray photoelectron emission microscopy (X-PEEM), and time-of-flight secondary ion mass spectrometry (TOF-SIMS) to determine the chemical and physical effects of such a deformation on both the coating and the interfacial region. While XPS analyses always showed a continuous coating with no significant effect of the deformation, TOF-SIMS and near-edge X-ray absorption fine structure (derived from X-PEEM) data indicated the presence of a certain density of porosity and pinholes in all coatings as well as sparse fissures and molecular fragmentation in the deformed ones. The smallness of the area fraction affected by the defects and the subtlety of the chemical changes could only be evidenced through the higher chemical sensitivity of these latter techniques.
authors.affiliation: Laboratory for Biomaterials and Bioengineering, Department of Materials Engineering & University Hospital Research Center, Laval University, Quebec City, Quebec G1K 7P4, Canada.
authors.forename: Penelope
authors.initials: P
authors.lastname: Hale
authors.forename: Stéphane
authors.initials: S
authors.lastname: Turgeon
authors.forename: Paula
authors.initials: P
authors.lastname: Horny
authors.forename: François
authors.initials: F
authors.lastname: Lewis
authors.forename: Narelle
authors.initials: N
authors.lastname: Brack
authors.forename: Grant
authors.initials: G
authors.lastname: Van Riessen
authors.forename: Paul
authors.initials: P
authors.lastname: Pigram
authors.forename: Diego
authors.initials: D
authors.lastname: Mantovani
mesh_terms: D000042:Absorption; D017611:Fluorine Compounds / Q000737:chemistry*; D008854:Microscopy, Electron / Q000379:methods*; D011108:Polymers / Q000737:chemistry*; D018629:Spectrometry, Mass, Secondary Ion / Q000379:methods*; D015607:Stents; D013997:Time Factors; D014965:X-Rays
chemical_list: D017611:Fluorine Compounds; D011108:Polymers