ISSN:
1662-9752
Quelle:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Thema:
Maschinenbau
Notizen:
Metallic Intravascular stents are medical devices used to scaffold a biological lumen,mostly diseased arteries, after balloon angioplasty. They are commonly made of 316L stainless steel orNitinol, two alloys containing Nickel, an element classified as potentially toxic and carcinogenic. Althoughthey are largely implanted, the long-term safety of such metallic elements is still controversial, since thecorrosion processes may lead to the release of several metallic ions. In order to avoid the metallic ion releasein the body and to improve the biocompatibility of metallic stents with their biological environments,polymer coatings have been deposited by two different technologies, i.e. plasma surface modifications andElectrospraying. The role of the polymer coating is then to encapsulate the stainless steel device, and tofavour the chemical grafting of Phosphorylcholine, a molecule known for its hemocompatible properties.1In this talk, the state of the art on low pressure and atmospheric pressure plasmas for deposition oforganic coatings will be given and we will present the advantages and drawbacks of each process. Then, wewill present an original technology that combine a Dielectric Barrier Discharge and an electrosprayingsystem to deposit well-defined Polyacrylic acid and Polyallylamine films. The advantage of such system isthe possibility to limit the extent of the monomer fragmentation and to give rise to rapid deposition of ahighly functionalised plasma polymer layer, and also the possibility to cover three dimensional objects, suchas stents. Thus, the theory of EHDA technology will be explained: special attention has been paid to definethe Electrospray parameters (Voltage, flow of precursor, nozzle-substrate distance…) which control the sizedistribution of the charged droplets and as a consequence, the structure of the film coating. The film coatingshave been analysed with XPS and by ATR. Moreover, special attention will be paid on the stability of thecoating which is related to both spraying conditions as well as to the preliminary plasma treatment. Thepotentiality and the features of the EHDA process will be then presented
Materialart:
Digitale Medien
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/14/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.529.pdf
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