Lecture-3SS-jpeg - Surface Properties – An Overview –...

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Unformatted text preview: Surface Properties – An Overview – Lecture Slide Set 3 Overview Dr. Anthony Brennan University of Florida Tel: 352.392.6281 Email: abrennan@mse.ufl.edu EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 1 Lecture 3 – Surface Properties Lecture Overview Overview • Learning Objectives: – Biomaterial Surfaces • • • • Reactive Distinct from Bulk Contamination Dynamic – Critical Parameters • Chemical Structure • Physical Structure – Method Specific Properties • Chemical – XPS, FTIR, WAXD, EDAX, Contact Angle, Chemical Radionucleotide, Derivatization Radionucleotide, • Physical – AFM, SEM, TEM, Ellipsometry, DTMA EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 2 Common Methods For Surface Characterization Common EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 3 Background • Adhesion – the molecular attraction Adhesion exerted between the surfaces of bodies in contact in • Molecular Interactions – Dispersion – Hydrogen bonding – Polar – Ionic – Acid-base UF Biofouling Group – Joint ONR/AMBIO Workshop - December 2006 UF Adhesion Theory Empirical Models Kendall Model for Elastomers GRC - Chemistry at Interfaces, Waterville Valley, July 2008 GRC Mechanisms of Adhesion • Classical “Wetting Theory” • where UF Biofouling Group – Joint ONR/AMBIO Workshop - December 2006 UF Assumptions • Vapor molecules are adsorbed by surface • Defined as: • For high energy liquid on low energy solid Spontaneous spreading occurs UF Biofouling Group – Joint ONR/AMBIO Workshop - December 2006 UF Young’s Equation • Assumes – – – – – – Homologous series of liquids No swelling of substrate Low vapor loss ‘Molecularly’ smooth surface No impurities Controlled drop size UF Biofouling Group – Joint ONR/AMBIO Workshop - December 2006 UF Determining Solid Surface Energies Determining UF Biofouling Group – Joint ONR/AMBIO Workshop - December 2006 Fowkes Approach UF Biofouling Group – Joint ONR/AMBIO Workshop - December 2006 UF Kaelbe’s Approach • Combine all non-dispersion Combine interactions interactions • Select low (H2O) and high (CH2Cl2) (H (CH Select surface tension fluids surface • “Quantitatively’ predicts adhesion – Fundamentally, need to correlate energies Fundamentally, with molecular structure and activity with UF Biofouling Group – Joint ONR/AMBIO Workshop - December 2006 UF Wenzel Wenzel • Fluid follows Fluid contours of topography topography • Roughness Factor r = Asurface/Aprojected • cos θ* = r cos θ cos cos Cassie & Baxter Cassie • Composite Surface Φs = Solid Fraction • Air Pockets cos θ* = Φscos θ – 1 cos cos Ultrahydrophobic • Wicking cos θ* = Φs(cos θ-1) + 1 cos (cos ultrahydrophilic Dimensions of Selected Surfaces Dimensions GRC - Chemistry at Interfaces, Waterville Valley, July 2008 Effect of Topography on Wetting Behavior Behavior Features Spacing (mm) Φs Smooth - 1 Pits 5 r Contact Angles (°) 1 108 ± 4 71 ± 6 55 ± 8 0.8 1.8 115 ± 2 65 ± 2 50 ± 8 0.91 1.4 112 ± 2 69 ± 4 52 ± 4 0.97 1.1 110 ± 6 65 ± 6 56 ± 6 5 0.75 2 133 ± 8 51 ± 2 39 ± 6 10 0.89 1.4 121 ± 6 62 ± 4 49 ± 8 20 0.96 1.2 116 ± 6 68 ± 12 48 ± 6 5 0.5 1.3 116 ± 8 63 ± 8 - 10 0.33 1.2 115 ± 8 63 ± 6 - 20 Ribs DMF 20 Ridges MeI 10 Channels Water 0.2 1.1 111 ± 6 66 ± 4 - 2 0.47 5 135 ± 3* 46 ± 8 35 ± 2 Model Correlation Model 40 y = 0.919x R² = 0.917 30 20 10 0 -40 -30 -20 -10 0 10 20 30 40 -10 T i g a h C t n c d e r P -20 -30 -40 Measured Percent Change in Theta • Model correlates well with experimental data • Useful tool for topography design Maximize the Effect Maximize • Maximize Wenzel slope Cassie Model 1 5x5x5 Channels – Increase r Increase • Requires high aspect Requires ratio features ratio Sharklet Sharklet 5x10 Channels 5x10 5x10 Ridges θ* – Decrease Φs Decrease -1 s o C • Minimize Cassie slope 0.5 0 -0.5 0 -0.5 Cos θ -1 0.5 1 UHMWPE FTIR-ATR UHMWPE Incidence Angle/Crystal Composition Unpublished Data by David Jackson, University of Florida, Biweekly Report 11/10/08 Depth of Penetration: Harrick, N. J. (1967). Internal Reflection Spectroscopy. New York, NY, Interscience Publishers. Effective Thickness Effective for Polarized: for Figure 1: S pectra of UHWMPE film with different crystals and different angles of incidence. Crystal (angle) (Degrees) Ge (40) Ge (60) ZnS (60) e PTP Noise RMS Noise PE signal Ratio De AU AU AU (@2900 cm-1) ------- microns 5.82E-04 1.33E-04 2.26E-01 388.58 0.52 7.70E-04 1.62E-04 3.94E-02 51.18 0.27 6.80E-04 1.48E-04 2.64E-01 388.12 1.32 Table 1: Measures of noise, signal, ratio and effective thickness. Fornel, F. d., Ed. (2000). Evanescent Waves: From Newtonian Optics to Atomic Optics. Springer Series in Optical Sciences. New York, NY, Springer. EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 18 SEM, XPS SEM, FIG. 4. Zr3d XPS spectrum of FIG. zirconia fiber. The sample was obtained via calcining at 800 °C. obtained FIG. 1. (a) FESEM image of Z rCF. (b) FESEM image of zirconia fiber, obtained at 800 ° C. (c) FESEM image of the carbonized Z rCF, the main axis of which runs from the upper left to the lower right corner. This FESEM image was obtained without any metal coating. (d) TEM image of zirconia fiber, obtained at 800 ° C. J. Mater. Res., Vol. 23, No. 12, Dec 2008 EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 FIG. 5. XRD patterns of ZrCF and FIG. zirconia fiber obtained at different calcining temperature, within 2 calcining range of 15°–80°. range 19 Summary • Surface characterization requires Surface constant monitoring of sample condition constant • Surfaces are dynamic, reactive and readily Surfaces contaminated contaminated • Modes include in vitro, in vivo, dry, high Modes vacuum, treatments/no treatments (microscopy) (microscopy) • Surfaces are distinct from bulk EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 20 Additional References • “Biomaterials Science – An Biomaterials Introduction to Materials in Medicine,” Ed. B. D. Ratner, A. S. Hoffman, F. J. Schoen, and J. E. Lemons, Academic Press, 1996, ISBN: 0-12-582460-2 Press, • Web resources listed in lecture EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 21 ...
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