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Long‐term in vitro stability assessment of polycarbonate urethane micro catheters: Resistance to oxidation and stress cracking
Author(s) -
Chandy Thomas,
Van Hee Justin,
Nettekoven William,
Johnson Jay
Publication year - 2009
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.31218
Subject(s) - materials science , scanning electron microscope , gel permeation chromatography , environmental stress cracking , polycarbonate , permeation , nuclear chemistry , stress corrosion cracking , chromatography , composite material , polymer , chemistry , corrosion , membrane , biochemistry
Micro catheter tubes were prepared from poly (carbonate urethane) (PCU, Bionate) and poly (ether urethane) (PEU, Pellethane) and their stability was investigated in vitro under applied strain. The tubes were stretched to an elongation of 200% or 300% and exposed to hydrogen peroxide/cobalt chloride (H 2 O 2 /CoCl 2 ) solution for specific periods of time (up to 10 months). The samples were observed for surface degradation via scanning electron microscopy, the bulk erosion via the weight difference, and the changes in molecular weight using gel permeation chromatography. The 200% and 300% strained Pellethane tubes kept in H 2 O 2 /CoCl 2 solution for 1 month showed substantial cracking of the surface layer with pitting and have degraded completely within 45 to 60 days (from scanning electron microscopy). Bionate tubes treated in similar conditions for a 10‐month period exhibited minute surface erosion in the depth of 0.25–1 μm and showed no evidence of major cracking or pitting. The gel permeation chromatography analysis of 300% strained catheters indicated that the degradation of Bionate tubes was negligible. The 10‐month samples had shown ∼18% reduction in their number average molecular weight ( M n ) and about 8% reduction in weight average molecular weight ( M w ). The Pellethane studied in similar conditions had indicated ∼72% reduction in M n and about ∼50% reduction in M w for 1 month. Overall, the Bionate underwent less degradation and the degradated surface layer was much thinner than Pellethane. These in vitro results are valuable in designing the in vivo studies for using Bionate tube as a long‐term implant. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009