Physics and Chemistry of Interfaces (eBook)

Hans-Jürgen Butt, Karlheinz Graf, Michael Kappl (Autoren)

eBook Download: EPUB

2023 | 4. Auflage
480 Seiten
Wiley-VCH (Verlag)
978-3-527-83616-1 (ISBN)

Infos

Physics and Chemistry of Interfaces

Comprehensive textbook on the interdisciplinary field of interface science, fully updated with new content on wetting, spectroscopy, and coatings

Physics and Chemistry of Interfaces provides a comprehensive introduction to the field of surface and interface science, focusing on essential concepts rather than specific details, and on intuitive understanding rather than convoluted math. Numerous high-end applications from surface technology, biotechnology, and microelectronics are included to illustrate and help readers easily comprehend basic concepts.

The new edition contains an increased number of problems with detailed, worked solutions, making it ideal as a self-study resource. In topic coverage, the highly qualified authors take a balanced approach, discussing advanced interface phenomena in detail while remaining comprehensible. Chapter summaries with the most important equations, facts, and phenomena are included to aid the reader in information retention.

A few of the sample topics included in Physics and Chemistry of Interfaces are as follows:

• Liquid surfaces, covering microscopic picture of a liquid surface, surface tension, the equation of Young and Laplace, and curved liquid surfaces
• Thermodynamics of interfaces, covering surface excess, internal energy and Helmholtz energy, equilibrium conditions, and interfacial excess energies
• Charged interfaces and the electric double layer, covering planar surfaces, the Grahame equation, and limitations of the Poisson-Boltzmann theory
• Surface forces, covering Van der Waals forces between molecules, macroscopic calculations, the Derjaguin approximation, and disjoining pressure

Physics and Chemistry of Interfaces is a complete reference on the subject, aimed at advanced students (and their instructors) in physics, material science, chemistry, and engineering. Researchers requiring background knowledge on surface and interface science will also benefit from the accessible yet in-depth coverage of the text.

Hans-Jürgen Butt is Director at the Max Planck Institute for Polymer Research in Mainz, Germany. His research topics include surface forces and wetting.

Karlheinz Graf is Professor for Physical Chemistry at the University of Applied Sciences (Hochschule Niederrhein) in Krefeld.

Michael Kappl is group leader at the Max Planck Institute for Polymer Research in Mainz, Germany. He investigates the adhesion and friction of micro- and nanocontacts and capillary forces.

Autor

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

Inhalt

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 Sur

Textauszug

2
Liquid Surfaces

2.1 Microscopic Picture of a Liquid Surface

A liquid surface is not an infinitesimal sharp boundary in the direction of its normal; it has a certain thickness. For example, if we consider the density normal to a surface (Figure 2.1), we can observe that, within a few molecules, the density decreases from that of the bulk liquid to that of its vapor [8].

The density is only one criterion by which one may define the thickness of an interface. Another possible parameter is the orientation of the molecules. For example, water molecules at the surface prefer to be oriented with their hydrogen atoms “out” toward the vapor phase. This orientation fades with increasing distance from the surface. At a distance of 0.5‐1 nm, the molecules are again randomly oriented like in the bulk.

Which thickness do we have to use? This depends on the relevant parameter. If we are interested, for instance, in the density of a water surface, a realistic thickness is on the order of 1 nm. Let us assume that a salt is dissolved in water. Then the concentration of ions might vary over a larger distance (characterized by the Debye length, Section 4.2.2). With respect to the ion concentration, the thickness is thus much larger. When in doubt, it is safer to choose a large value for the thickness.

The surface of a liquid is a very turbulent place. Molecules may evaporate from the liquid into the vapor phase and vice versa. In addition, they diffuse into the bulk phase and molecules from the bulk diffuse to the surface.

Example 2.1 To estimate the number of gas molecules hitting a liquid surface per second, we recall the kinetic theory of ideal gases. In textbooks on physical chemistry, the rate of effusion of an ideal gas through a small hole is given by

(2.1)

Here, is the cross‐sectional area of the hole and is the molecular mass. This is equal to the number of water molecules hitting the surface area per second. Water at 25 °C has a vapor pressure of 3168 Pa. With a molecular mass of kg, water molecules per second hit a surface area of 10 . In equilibrium, the same number of molecules escapes from the liquid phase. The area covered by one water molecule is approximately 10 . Thus, the average time a water molecule remains on the surface is in the order of 0.1 .

Figure 2.1 Snapshot of molecular structure of water as obtained by computer simulation and density of water versus coordinate normal to its surface [9]. The density in water vapor at saturation and 25 °C is only 0.02 g/. Therefore, it is negligible on the scale plotted (kindly provided by D. Horinek).

2.2 Surface Tension

The following experiment helps us to define the most fundamental quantity in surface science: the surface tension. A liquid film is spanned over a frame with a mobile slider (Figure 2.2). The film is relatively thick, say 1 , so that the distance between the back and front surfaces is large enough to avoid overlapping of the two interfacial regions. Practically, this experiment might be tricky even in the absence of gravity, but it violates no physical laws, so in principle, it is feasible. If we increase the surface area by moving the slider a distance to the right, work must be done. This work is proportional to the increase in surface area . The surface area increases by twice because the film has a front and back side. Introducing the proportionality constant , we get

(2.2)

The constant is called surface tension.

Equation (2.2) is an empirical law and a definition at the same time. The empirical law states that the work is proportional to the change in surface area. This is not only true for infinitesimally small changes in (which is trivial) but also for significant increases in the surface area: . In general, the proportionality constant depends on the composition of the liquid and the vapor, temperature, and pressure, but it is independent of the area. By definition, we call the proportionality constant surface tension.

Figure 2.2 Schematic setup to verify Eq. (2.2) and define the surface tension.

The surface tension can also be defined by the force required to hold the slider in place and to balance the surface tensional force:

(2.3)

Both forms of the law are equivalent, provided that the process is reversible. Then we can write

(2.4)

The force is directed to the left, while increases to the right. Therefore, we have a negative sign.

The unit of surface tension is either joule per square meter or newton per meter. Surface tensions of liquids are on the order of 0.02–0.08 N/m (Table 2.1). For convenience, they are usually given in millinewtons per meter (or ).

Empirically one finds that the surface tension of liquids decreases linearly with temperature. Thus, if we know the surface tension at a given temperature , then we can approximate the surface tension at a temperature according to

(2.5)

The coefficient is negative. As we will see in Chapter 3, is equal to the surface entropy.

Example 2.2 If a water film is formed on a frame with a slider length of 1 cm, then the film pulls on the slider with a force of

That corresponds to a weight of 0.15 g.

Example 2.3 Calculate the surface tension of water at . With and /(K m) at (Table 2.1), we get

This is close to the experimental value of 67.9 mN/m.

The term surface tension is tied to the concept that the surface stays under a tension. In a way, this is similar to a rubber balloon, where a force is required as well to increase the surface area of its rubber membrane against a tension. There is, however, a difference: while the expansion of a liquid surface is a plastic process and the surface tension remains constant, the stretching of a rubber membrane is usually elastic, and the tension increases with increasing surface area.

Table 2.1 Surface tensions and of some liquids at different temperatures [10].

Substance

Water

25

71.99

−15.6 × 10−5

Methanol

25

22.07

−7.73 × 10−5

Ethanol

25

21.97

−8.33 × 10−5

1‐Propanol

25

23.32

−7.75 × 10−5

1‐Butanol

25

24.93

−8.98 × 10−5

2‐Butanol

25

22.54

−7.95 × 10−5

Phenol

50

38.20

−10.7 × 10−5

Glycerol

25

63.70

−5.98 × 10−5

Cyclohexane

25

24.65

−11.9 × 10−5

Benzene

25

28.22

−12.9 × 10−5

Toluene

25

27.93

−11.8 × 10−5

‐Pentane

25

15.49

−11.1 × 10−5

‐Hexane

25

17.89

−10.2 × 10−5

‐Heptane

25

19.65

−9.80 × 10−5

‐Octane

25

21.14

−9.51 × 10−5

‐Nonane

25

22.38

−9.36 × 10−5

‐Decane

25

23.37

−9.20 × 10−5

Acetone

25

23.46

−11.2 × 10−5

Formamide

25

57.03

−8.44 × 10−5

Dichloromethane

25

27.20

−12.8 × 10−5

Chloroform

25

26.67

−12.9 × 10−5

Decaline

25

31.0

−10.3 × 10−5

PDMS

25

19.0–20.4

−3.65 × 10−5

Hexamethyldisiloxane

25

15.70

−8.77 × 10−5

Octamethylcyclotetrasiloxane

25

17.61

−6.60 × 10−5

...

Perfluorohexane

25

12.03

−10.5 × 10−5

Produkt-Details

• Erscheint lt. Verlag: 7.2.2023
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Physik / Astronomie ► Atom- / Kern- / Molekularphysik
• Schlagworte: Chemie • Chemistry • Condensed Matter • Dünne Schichten, Oberflächen u. Grenzflächen • Grenzfläche • Kondensierte Materie • Materials Science • Materialwissenschaften • Oberflächenphysik • Physical Chemistry • Physics • Physik • Physikalische Chemie • Thin Films, Surfaces & Interfaces
• ISBN-10: 3-527-83616-0 / 3527836160
• ISBN-13: 978-3-527-83616-1 / 9783527836161