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lecture10 - 3.051J/20.340J Lecture 10: Surface Modification...

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1 3.051 J / 20 .340 J Lecture 10: Surface Modification of Biomaterials (Part II) Surface Modification Methods A. Plasma Treatments Plasmas : ionized gases (ions, electrons, free radicals, atoms, molecules) created by ion/electron impact under applied E-field: A + e A + + 2e Uses 1. surface etching ¾ employs inert gases (e.g., Ar) ¾ purposes: remove impurities, increase roughness 2. surface reactions ¾ crosslink polymer surfaces modify transport properties, reduce surface mobility ¾ generate surface functional groups or γ 1 , create reactive surfaces O 2 , CO 2 , CO : -C-O-, -C=O, -O-C=O, -C-O-O N 2 , NO 2 , NO (nitric oxide) : -C-N, -C=N, -C N (plus above) NH 3 (ammonia) : -NH, -NH 2 (plus above) CF 4 , C 2 F 6 (hexafluorethane) : -CF, -CF 2 , -CF 3
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2 3.051 J / 20 .340 J Drawbacks: a. ill-defined surface chemistries b. reconstruction nullifies treatment θ a O 2 -plasma treated HDPE - - - 90 PDMS 40 4 8 t i m e ( h r s ) 3. Coating Depositions ¾ graft polymerized layers plasma + monomer radically-polymerized surface layer hydrophilic monomers: hydroxyethyl methacrylate (HEMA), N- vinyl-2-pyrollidone (NVP), methacrylic acid (MAA), acrylamide (AAm), etc. H 2 C=CH H 2 C=CH H 2 C=CCH 3 H 2 C=CH C=O C=O C=O O O N O N H H 2 CH 2 CH 2 OH
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3 3.051 J / 20 .340 J ¾ plasma-sprayed coatings (inorganics) fine powders injected in plasma partial melting gives surface adhesion HA (hydroxyapatite): bone bonding Al 2 O 3 : hardness CoCr, Ti: surface roughness/porosity bone bonding Four photos removed for copyright reasons. Ti-Al-V implant with a) smooth surface; b) Ti plasma spray coating. Micrographs show bonding with bone after 4 weeks implantion in a canine. P = PMMA cement. B = new bone tissue. (B.H. Lee et al., J. Biomed. Mater. Res. 69A , 279 (2004))
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3.051 J / 20 .340 J 4 B. Other Orthopedic Biomaterial Treatments ¾ Ion implantation: high energy ion beam buries atoms into near- surface (up to 10 6 eV) (metals) hardness & wear resistance corrosion resistance ex. N implantation in Ti ¾ Electrolytic coatings hardness & wear resistance
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lecture10 - 3.051J/20.340J Lecture 10: Surface Modification...

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