Surface and Interfacial Aspects of Biomedical Polymers

This book is intended to provide a fundamental basis for the study of the interaction of polymers with living systems, biochemicals, and with aqueous solutions. The surface chemistry and physics of polymeric materials is a subject not normally covered to any significant extent in classical surface chemistry textbooks. Many of the assumptions of classical surface chemistry are invalid when applied to polymer surfaces. Surface properties of polymers are important in the development of medical devices and diagnostic products. Surface properties are also of vital importance in fields such as adhesion, paints and coatings, polymer-filler interactions, heterogeneous catalysis, composites, and polymers for energy generation. The book begins with a chapter considering the current sources of information on polymer surface chemistry and physics. It moves on to consider the question of the dynamics of polymer surfaces and the implica­ tions of polymer surface dynamics on all subsequent characterization and interfacial studies. Two chapters are directed toward the question of model polymers for preparing model surfaces and interfaces. Complete treatments of X-ray photoelectron spectroscopy and attenuated total reflection infrared spectroscopy are given. There is a detailed treatment of the contact angle with particular emphasis on contact angle hysteresis in aqueous systems, followed by chapters on interfacial electrochemistry and interface acid-base charge-transfer properties. The very difficult problem of block and graft copolymer surfaces is also discussed. The problem of theoretical calculations of surface and interfacial tensions is presented. Raman spectroscopy is considered as an analytical technique for polymer surface characterization.

1. Introduction to Surface Chemistry and Physics of Polymers.- 1. Sources.- 2. Objectives.- 3. Overview.- 4. Limitations.- 5. References.- 2. Polymer Surface Dynamics.- 1. Introduction.- 2. Polymer Transitions and Relaxations.- 3. Probing Polymer Motions and Transitions.- 3.1. Bulk Methods.- 3.2. Inverse Gas Chromatography (IGC).- 4. Polymer Surface Motions.- 4.1. Inverse GC.- 4.2. Filled Systems.- 4.3. Contact Angle Methods.- 4.4. Other Methods.- 5. Conclusions.- 6. Summary.- Acknowledgments.- References.- 3. Model Polymers for Probing Surface and Interfacial Phenomena.- 1. Introduction.- 2. Stereoregular Polymers.- 2.1. Purpose (Stereochemistry).- 2.2. Chemistry.- 2.3. Bulk Properties.- 2.4. Surface Characterization.- 3. Hydroxyethyl Methacrylate Copolymers.- 3.1. Purpose (Systemic Hydration).- 3.2. Chemistry.- 3.3. Bulk Properties.- 3.4. Surface Characteristics.- 4. Block Copolymers.- 4.1. Purpose (Morphology).- 4.2. Styrene-Hydroxylated Butadiene-Styrene Triblocks.- 4.3. HEMA-Styrene-HEMA Triblocks.- 5. Alkyl Methacrylates.- 5.1. Purpose (Systematic Change in Tg).- 5.2. Chemistry.- 5.3. Bulk Characteristics.- 5.4. Surface Characteristics.- 6. Derivatized Agarose.- 6.1. Purpose (Modification for Systemic Hydrophobicity).- 6.2. Chemistry.- 6.3. Bulk Characteristics.- 6.4. Surface Characteristics.- 7. Polyurethanes.- 7.1. Purpose (Practical Biomedical Elastomers).- 7.2. Chemistry.- 7.3. Bulk Properties.- 7.4. Surface Characteristics.- 8. Poly(?-Amino Acids).- 8.1. Purpose (Naturally Occurring Repeat Units).- 8.2. Chemistry.- 8.3. Surface Analysis.- 9. Summary/Conclusions.- Acknowledgments.- References.- 4. Polymeric Oriented Monolayers and Multilayers as Model Surfaces.- 1. Introduction.- 1.1. Biological Membranes.- 1.2. Models for Biomembranes.- 1.3. Characterization of Mono- and Multilayers.- 1.4. Stability of Conventional Model Membrane Systems.- 2. Polymerized Model Membranes.- 2.1. Polymerizable Lipids.- 2.2. Polymerized Monolayers.- 2.2.1. Monolayers with One Component.- 2.2.2. Mixed Monolayers.- 2.3. Polymeric Multilayers.- 2.4. Polymeric Black Lipid Membranes.- 2.5. Polymeric Vesicles (Liposomes).- 3. Conclusions.- References.- 5. X-ray Photoelectron Spectroscopy (XPS).- 1. Introduction.- 2. Basic Principles of XPS.- 2.1. The Photoelectric Effect.- 2.2. Basic Experiment.- 2.3. Instrument.- 2.3.1. X-ray Source.- 2.3.2. Sample.- 2.3.3. Analyzer/Detector.- 2.3.4. Instrument Sources.- 2.4. Charging and Energy Referencing.- 2.5. Spectra and Spectral Features.- 3. Elemental Analysis.- 3.1. Qualitative and Semiquantitative Analysis.- 3.2. Quantitative Elemental Analyses.- 3.2.1. Basics.- 3.2.2. X-ray Flux, I0.- 3.2.3. Differential Photoionization Cross Section, ?i,k.- 3.2.4. Instrument Transmission or Throughput Function, Ti,k.- 3.2.5. Mean Free Path, ?i,k.- 3.2.6. Measured Intensities, Ni,k.- 3.2.7. Quantitative Analysis Summary.- 4. Chemical Bonding.- 4.1. Chemical Shifts.- 4.2. Energy Referencing.- 4.3. Initial and Final States.- 4.4. Auger Processes.- 4.5. Shake-up Satellites.- 4.6. Multiplet Splitting.- 4.7. Molecular Orbitals.- 4.8. Summary.- 5. Functional Group Labelling.- 6. Data Processing.- 6.1. Curve Resolution.- 6.2. Smoothing.- 6.3. Derivatives.- 6.4. Deconvolution.- 6.5. Summary.- 7. Variable Angle Methods.- 7.1. Introduction.- 7.2. Mean Free Paths.- 7.3. Uniform Overlayers.- 7.4. Patchy Overlayers.- 7.5. Surface Concentration Gradients.- 7.6. Limitations.- Acknowledgments.- References.- 6. Surface Infrared Spectroscopy.- 1. Introduction.- 2. Infrared Spectroscopy.- 3. Principles of Internal Reflection.- 3.1. Electromagnetic Radiation Described as Waves.- 3.1.1. Vectorial Properties of Electromagnetic Waves.- 3.1.2. Energy Flux of Electromagnetic Radiation.- 3.2. Reflection and Refraction of Electromagnetic Waves at an Interface.- 3.3. Total Internal Reflection.- 3.3.1. Presence of an Electromagnetic Field in the Second Medium.- 3.3.2. Sampling the Electromagnetic Field in the Second Medium.- 3.3.3. Sampling Depth of Electromagnetic Field in the Second Medium.- 3.3.4. Sampling Depth as a Function of Experimental Variables.- 4. Polymer Applications of Total Internal Reflection Infrared Spectroscopy.- 4.1. Surface Molecular Structure.- 4.2. Surface Orientation.- 4.3. Surface Morphology.- 5. Summary.- Acknowledgment.- References.- 7. The Contact Angle and Interface Energetics.- 1. Introduction.- 2. Fundamentals.- 2.1. Surface and Interface Conventions, Definitions, and Semantics.- 2.2. Two-Phase Equilibria—The Liquid/Vapor and Liquid/Liquid Interfaces.- 2.3. Three-Phase Equilibria.- 2.3.1. Ideally Deformable Phases: The L/L/V Interface.- 2.3.2. Ideally Nondeformable Phases: The S/L/V Interface.- 2.4. Equilibrium.- 2.5. Surface and Interfacial Tension Measurement.- 3. Contact Angle Measurement.- 3.1. Assumptions.- 3.2. Methods.- 3.3. Critical Surface Tension, ?c.- 3.4. Captive Bubble (Underwater) Method.- 4. Contact Angle Hysteresis.- 4.1. Background.- 4.2. Hysteresis.- 4.3. Roughness.- 4.4. Surface Heterogeneity.- 4.5. Deformation.- 4.6. Swelling and Penetration.- 4.7. Surface Reorientation and Mobility.- 4.8. Surface Entropy.- 5. Interfacial Energetics.- 6. Charge Effects.- 7. Conclusions.- Acknowledgments.- References.- 8. Interfacial Electrochemistry of Surfaces with Biomedical Relevance.- 1. Introduction.- 2. Basic Electrical Parameters.- 2.1. Charge.- 2.2. Potential.- 2.3. Other Important Electrical Characteristics.- 3. Double Layer Models.- 3.1. The Molecular Condenser.- 3.2. The Diffuse Double Layer.- 3.3. The Gouy-Stern Double Layer.- 3.4. Porous Double Layers.- 4. Double Layer Theory.- 4.1. Gouy-Chapman Theory.- 4.2. Inner Layer Theory.- 4.3. Porous Double Layers.- 5. Interpretation of Electrokinetic Potentials.- 6. Experimental.- 6.1. The Surface Charge.- 6.2. The Electrokinetic Charge and Potential.- 7. Conclusions.- References.- 9. Interface Acid-Base/Charge-Transfer Properties.- 1. The Acid-Base Character of “Polar” Interactions.- 2. The Surface Acidity or Basicity of Polymers.- 2.1. Infrared Measurements of Acid-Base Polymer Interactions.- 2.2. Contact Angle Measurements of Surface Acidity or Basicity.- 3. The Surface Acidity or Basicity of Inorganic Surfaces.- 3.1. Adsorption of Polymers on Inorganic Surfaces.- 3.2. Heats of Adsorption of Organic Acids and Bases on Inorganic Powders.- 4. Charge Transfer between Phases.- 4.1. Charge Transfer between Inorganic Solids and Organic Liquids.- 4.2. Charge Injection into Organic Polymers.- 4.3. Semiconductor Devices for Sensing Charge Injection into Polymers.- Acknowledgment.- References.- 10. Graft Copolymer and Block Copolymer Surfaces.- 1. Introduction.- 2. Graft Copolymer Surfaces.- 3. Block Copolymer Surfaces.- 4. Segmented Polyurethanes.- Acknowledgments.- References.- 11. Interfacial Tensions at Amorphous Polymer-Water Interfaces: Theory.- 1. Introduction.- 2. The Theory of Surface and Interfacial Tensions of Amorphous High Polymers.- 2.1. Lattice Theories.- 2.2. Significant Structure Theory.- 2.3. Scaled Particle Theories.- 2.4. Self-Consistent Field Theory.- 2.5. Thermodynamic Theory.- 2.6. Geometric Mean and Harmonic Mean Theories.- 2.7. Regular Solution Theory.- 3. The Theory of Interfacial Tension at Polymer-Water Interfaces.- 3.1. Surface Tension of Water.- 3.2. Interfacial Tension at Polymer-Water Interfaces.- References.- 12. Surface Raman Spectroscopy.- 1. Introduction.- 2. Raman Scattering Effect.- 3. Surface and Thin Film Raman Spectroscopy.- 3.1. External Reflection.- 3.2. Total Internal Reflection (TIR).- 3.3. Waveguide Methods.- 3.4. Plasmon Enhancement.- 3.5. Surface-Enhanced Raman Spectroscopy (SERS).- 4. Instrumental Improvements.- 5. Conclusion.- Acknowledgments.- References.- 13. Polymer Surface Analysis: Conclusions and Expectations.- 1. Introduction.- 2. Microscopy.- 3. Expectations.- 3.1. Ion Beam Methods—SIMS and ISS.- 3.2. Photoelectron Microscopy and Imaging XPS.- 3.3. Surface Fluorescence Spectroscopy.- 3.4. Surface Modification.- 3.5. Reference Surfaces.- 3.6. Scanning Ellipsometry.- 3.7. Other.- 4. Conclusions.- References.