Physics and Chemistry of Interfaces

1. Introduction

2. Liquid Surfaces
2.1 Microscopic Picture of a Liquid Surface
2.2 Surface Tension
2.3 Equation of Young and Laplace
2.3.1 Curved Liquid Surfaces
2.3.2 Derivation of Young-Laplace Equation
2.3.3 Applying the Young-Laplace Equation
2.4 Techniques to Measure Surface Tension
2.5 Kelvin Equation
2.6 Capillary Condensation
2.7 Nucleation Theory
2.8 Summary
2.9 Exercises

3. Thermodynamics of Interfaces
3.1 Thermodynamic Functions for Bulk Systems
3.2 Surface Excess
3.3 Thermodynamic Relations for Systems with an Interface
3.3.1 Internal Energy and Helmholtz Energy
3.3.2 Equilibrium Conditions
3.3.3 Location of Interface
3.3.4 Gibbs Energy and Enthalpy
3.3.5 Interfacial Excess Energies
3.4 Pure Liquids
3.5 Gibbs Adsorption Isotherm
3.5.1 Derivation
3.5.2 System of Two Components
3.5.3 Experimental Aspects
3.5.4 Marangoni Effect
3.6 Summary
3.7 Exercises

4. Charged Interfaces and the Electric Double Layer
4.1 Introduction
4.2 Poisson-Boltzmann Theory of Diffuse Double Layer
4.2.1 Poisson-Boltzmann Equation
4.2.2 Planar Surfaces
4.2.3 The Full One-Dimensional Case
4.2.4 The Electric Double Layer around a Sphere
4.2.5 Grahame Equation
4.2.6 Capacitance of Diffuse Electric Double Layer
4.3 Beyond Poisson-Boltzmann Theory
4.3.1 Limitations of Poisson-Boltzmann Theory
4.3.2 Stern Layer
4.4 Gibbs Energy of Electric Double Layer
4.5 Electrocapillarity
4.5.1 Theory
4.5.2 Measurement of Electrocapillarity
4.6 Examples of Charged Surfaces
4.7 Measuring Surface Charge Densities
4.7.1 Potentiometric Colloid Titration
4.7.2 Capacitances
4.8 Electrokinetic Phenomena: the Zeta Potential
4.8.1 Navier-Stokes Equation
4.8.2 Electro-Osmosis and Streaming Potential
4.8.3 Electrophoresis and Sedimentation Potential
4.9 Types of Potential
4.10 Summary
4.11 Exercises

5. Surface Forces
5.1 Van der Waals Forces between Molecules
5.2 Van der Waals Force between Macroscopic Solids
5.2.1 Microscopic Approach
5.2.2 Macroscopic Calculation - Lifshitz Theory
5.2.3 Retarded Van der Waals Forces
5.2.4 Surface Energy and the Hamaker Constant
5.3 Concepts for the Description of Surface Forces
5.3.1 The Derjaguin Approximation
5.3.2 Disjoining Pressure
5.4 Measurement of Surface Forces
5.5 Electrostatic Double-Layer Force
5.5.1 Electrostatic Interaction between Two Identical Surfaces
5.5.2 DLVO Theory
5.6 Beyond DLVO Theory
5.6.1 Solvation Force and Confined Liquids
5.6.2 Non-DLVO Forces in Aqueous Medium
5.7 Steric and Depletion Interaction
5.7.1 Properties of Polymers
5.7.2 Force between Polymer-Coated Surfaces
5.7.3 Depletion Forces
5.8 Spherical Particles in Contact
5.9 Summary
5.10 Exercises

6. Contact Angle Phenomena and Wetting
6.1 Young's Equation
6.1.1 Contact Angle
6.1.2 Derivation
6.1.3 Line Tension
6.1.4 Complete Wetting and Wetting Transitions
6.1.5 Theoretical Aspects of Contact Angle Phenomena
6.2 Important Wetting Geometries
6.2.1 Capillary Rise
6.2.2 Particles at Interfaces
6.2.3 Network of Fibers
6.3 Measurement of Contact Angles
6.3.1 Experimental Methods
6.3.2 Hysteresis in Contact Angle Measurements
6.3.3 Surface Roughness and Heterogeneity
6.3.4 Superhydrophobic Surfaces
6.4 Dynamics of Wetting and Dewetting
6.4.1 Spontaneous Spreading
6.4.2 Dynamic Contact Angle
6.4.3 Coating and Dewetting
6.5 Applications
6.5.1 Flotation
6.5.2 Detergency
6.5.3 Microfluidics
6.5.4 Electrowetting
6.6 Thick Films: Spreading of One Liquid on Another
6.7 Summary
6.8 Exercises

7. Solid Surfaces
7.1 Introduction
7.2 Description of Crystalline Surfaces
7.2.1 Substrate Structure
7.2.2 Surface Relaxation and Reconstruction
7.2.3 Description of Adsorbate Structures
7.3 Preparation of Clean Surfaces
7.3.1 Thermal Treatment
7.3.2 Plasma or Sputter Cleaning
7.3.3 Cleavage
7.3.4 Deposition of Thin Films
7.4 Thermodynamics of Solid Surfaces
7.4.1 Surface Energy, Surface Tension, and Surface Stress
7.4.2 Determining Surface Energy
7.4.3 Surface Steps and Defects
7.5 Surface Diffusion
7.5.1 Theoretical Description of Surface Diffusion
7.5.2 Measurement of Surface Diffusion
7.6 Solid-Solid Interfaces
7.7 Microscopy of Solid Surfaces
7.7.1 Optical Microscopy
7.7.2 Electron Microscopy
7.7.3 Scanning Probe Microscopy
7.8 Diffraction Methods
7.8.1 Diffraction Patterns of Two-Dimensional Periodic Structures
7.8.2 Diffraction with Electrons, X-Rays, and Atoms
7.9 Spectroscopic Methods
7.9.1 Optical Spectroscopy of Surfaces
7.9.2 Spectroscopy Using Mainly Inner Electrons
7.9.3 Spectroscopy with Outer Electrons
7.9.4 Secondary Ion Mass Spectrometry
7.10 Summary
7.11 Exercises

8. Adsorption
8.1 Introduction
8.1.1 Definitions
8.1.2 Adsorption Time
8.1.3 Classification of Adsorption Isotherms
8.1.4 Presentation of Adsorption Isotherms
8.2 Thermodynamics of Adsorption
8.2.1 Heats of Adsorption
8.2.2 Differential Quantities of Adsorption and Experimental Results
8.3 Adsorption Models
8.3.1 Langmuir Adsorption Isotherm
8.3.2 Langmuir Constant and Gibbs Energy of Adsorption
8.3.3 Langmuir Adsorption with Lateral Interactions
8.3.4 BET Adsorption Isotherm
8.3.5 Adsorption on Heterogeneous Surfaces
8.3.6 Potential Theory of Polanyi
8.4 Experimental Aspects of Adsorption from Gas Phase
8.4.1 Measuring Adsorption to Planar Surfaces
8.4.2 Measuring Adsorption to Powders and Textured Materials
8.4.3 Adsorption to Porous Materials
8.4.4 Special Aspects of Chemisorption
8.5 Adsorption from Solution
8.6 Summary
8.7 Exercises

9. Surface Modification
9.1 Introduction
9.2 Physical and Chemical Vapor Deposition
9.2.1 Physical Vapor Deposition
9.2.2 Chemical Vapor Deposition
9.3 Soft Matter Deposition
9.3.1 Self-Assembled Monolayers
9.3.2 Physisorption of Polymers
9.3.3 Polymerization on Surfaces
9.3.4 Plasma Polymerization
9.4 Etching Techniques
9.5 Lithography
9.6 Summary
9.7 Exercises

10. Friction, Lubrication, and Wear
10.1 Friction
10.1.1 Introduction
10.1.2 Amontons' and Coulomb's Law
10.1.3 Static, Kinetic, and Stick-Slip Friction
10.1.4 Rolling Friction
10.1.5 Friction and Adhesion
10.1.6 Techniques to Measure Friction
10.1.7 Macroscopic Friction
10.1.8 Microscopic Friction
10.2 Lubrication
10.2.1 Hydrodynamic Lubrication
10.2.2 Boundary Lubrication
10.2.3 Thin-Film Lubrication
10.2.4 Superlubricity
10.2.5 Lubricants
10.3 Wear
10.4 Summary
10.5 Exercises

11. Surfactants, Micelles, Emulsions, and Foams
11.1 Surfactants
11.2 Spherical Micelles, Cylinders, and Bilayers
11.2.1 Critical Micelle Concentration
11.2.2 Influence of Temperature
11.2.3 Thermodynamics of Micellization
11.2.4 Structure of Surfactant Aggregates
11.2.5 Biological Membranes
11.3 Macroemulsions
11.3.1 General Properties
11.3.2 Formation
11.3.3 Stabilization
11.3.4 Evolution and Aging
11.3.5 Coalescence and Demulsification
11.4 Microemulsions
11.4.1 Size of Droplets
11.4.2 Elastic Properties of Surfactant Films
11.4.3 Factors Influencing the Structure of Microemulsions
11.5 Foams
11.5.1 Classification, Application, and Formation
11.5.2 Structure of Foams
11.5.3 Soap Films
11.5.4 Evolution of Foams
11.6 Summary
11.7 Exercises

12. Thin Films on Surfaces of Liquids
12.1 Introduction
12.2 Phases of Monomolecular Films
12.3 Experimental Techniques to Study Monolayers
12.3.1 Optical Microscopy
12.3.2 Infrared and Sum Frequency Generation Spectroscopy
12.3.3 X-Ray Reflection and Diffraction
12.3.4 Surface Potential
12.3.5 Rheologic Properties of Liquid Surfaces
12.4 Langmuir-Blodgett Transfer
12.5 Summary
12.6 Exercises

13. Solutions to Exercises

14. Analysis of Diffraction Patterns
14.1 Diffraction at Three-Dimensional Crystals
14.1.1 Bragg Condition
14.1.2 Laue Condition
14.1.3 Reciprocal Lattice
14.1.4 Ewald Construction
14.2 Diffraction at Surfaces
14.3 Intensity of Diffraction Peaks

Appendix A Symbols and Abbreviations
References
Index

Hans-Jürgen Butt is Director at the Max Planck Institute of Polymer Research in Mainz, Germany. He studied physics in Hamburg and Göttingen, Germany. Then he went to the Max-Planck-Institute of Biophysics in Frankfurt to work in Ernst Bamberg's group. After receiving his Ph.D. in 1989 he went as a post-doc to Santa Barbara, California. From 1990-95 he spent as a researcher back in Germany at the Max-Planck-Institute for Biophysics. In 1996 he became associate professor for physical chemistry at the University Mainz, three years later full professor at the University of Siegen. Only two years later he joined the Max Planck Institute of Polymer Research in Mainz and became director for Experimental Physics. His research topics include Surface forces and wetting.

Karlheinz Graf graduated at the Institute for Physical Chemistry in Mainz, and spent a postdoc at the University of California, Santa Barbara (UCSB). He has served as Project leader at the Max-Planck-Institute for Polymer Research, where his research concentrated on droplet evaporation, the structuring of polymer surfaces, and on constructing a special device for measuring forces between a solid surface and an adaptive lipid monolayer in a Langmuir trough. Afterwards he was acting Professor in Physical and Analytical Chemistry at the University of Siegen. After a short period at the University of Duisburg-Essen he became Professor for Physical Chemistry at the University of Applied Sciences (Hochschule Niederrhein) in Krefeld.

Michael Kappl studied physics at the University of Regensburg and the Technical University of Munich, and did his PhD thesis work in Ernst Bamberg's group at the Max Planck Institute of Biophysics in Frankfurt. After a year of postdoctoral research at the University of Mainz in the group of Prof. Butt, he worked as a consultant for Windows NT network solutions at the Pallas Soft AG, Regensburg. In 2000, he rejoined the group of Hans-Jürgen Butt. Since 2002 he is group leader at the Max Planck Institute for Polymer Research. By using focused ion beam methods, his investigates the adhesion and friction of micro- and nanocontacts, and capillary forces