INTERMOLECULAR AND SURFACE FORCES

Transcription

1 INTERMOLECULAR AND SURFACE FORCES SECOND EDITION JACOB N. ISRAELACHVILI Department of Chemical & Nuclear Engineering and Materials Department University of California, Santa Barbara California, USA ACADEMIC PRESS Harcourt Brace Jovanovich, Publishers London San Diego New York Boston Sydney Tokyo Toronto

2 Contents PART ONE The Forces Between Atoms and Molecules: Principles and Concepts Chapter 1 Historical Perspective The four forces of nature Greek and medieval notions of intermolecular forces Early scientific period: contrasts with gravitational forces First successful phenomenological theories Modern view of the origin of intermolecular forces Recent trends 11 Chapter 2Some Thermodynamic Aspects of Intermolecular 16 Forces 2.1 Interaction energies of molecules in free space and in a 16 medium 2.2 The Boltzmann distribution The distribution of molecules and particles in systems at 21 equilibrium 2.4 The van der Waals equation of state The criterion of the thermal energy kt for gauging the 24 strength of an interaction 2.6 Classification of forces 27 Chapter 3Strong Intermolecular Forces: Covalent and Coulomb 31 Interactions 3.1 Covalent or chemical bonding forces Physical and chemical bonds 32 v

3 vi CONTENTS 3.3 Coulomb forces or charge-charge interactions lonic crystals Reference states Range of Coulomb forces The Born energy of an ion Solubility of Ions in different solvents Specific ion-solvent effects Continuum approach Molecular approach: computer simulations 44 Chapter 4 Interactions Involving Polar Molecules What are polar molecules? Dipole seif-energy Ion-dipole interactions Ions in polar solvents Strong ion-dipole interactions: hydrated Ions Solvation forces, structural forces, hydration forces Dipole-dipole interactions Rotating dipoles and angle-averaged potentials Entropic effects 63 Chapter 5 Interactions Involving the Polarization of Molecules The polarizability of atoms and molecules The polarizability of polar molecules Interactions between Ions and uncharged molecules Ion-solvent molecule interactions and the Born energy Dipole-induced dipole interactions Unification of polarization interactions Solvent effects and 'excess polarizabilities' 76 Chapter 6 van der Waals Forces Origin of the van der Waals dispersion force between 83 neutral molecules: the London equation 6.2 Strength of dispersion forces: van der Waals solids and 85 Iiquids 6.3 van der Waals equation of state Gas-liquid and liquid-solid phase transitions van der Waals forces between polar molecules General theory of van der Waals forces between molecules 96

4 CONTENTS vii 6.7 van der Waals forces in a medium Dispersion self-energy of a molecule in a medium Further aspects of van der Waals forces: anisotropy, non- 105 additivity and retardation effects Chapter 7 Repulsive Forces, Total Intermolecular Pair Potentials 109 and Liquid Structure 7.1 Sizes of atoms, molecules and ions Repulsive potentials Total intermolecular pair potentials Role of repulsive forces in non-covalently bonded solids Role of repulsive forces in liquids: liquid structure Effect of liquid structure an molecular forces 119 Chapter 8 Special lnteractions: Hydrogen-Bonding, 122 Hydrophobic and Hydrophilic Interactions 8.1 The unique properties of water The hydrogen bond Models of water and associated liquids Relative strengths of different types of interactions The hydrophobic effect The hydrophobic interaction Hydrophilicity 133 PART TWO The Forces Between Particles and Surfaces Chapter 9 Some Unifying Concepts in Intermolecular and 139 Interparticle Forces 9.1 Factors favouring the association of like molecules or 139 particles in a medium 9.2 Two like surfaces coming together in a medium: surface 144 and interfacial energy 9.3 Factors favouring the association of unlike molecules, 145 particles or surfaces in a third medium 9.4 Particle surface interactions 147

5 VIII CONTENTS 9.5 Adsorbed surface films: wetting and non-wetting 149 Chapter 10 Contrasts Between Intermolecular, Interparticle and 152 Intersurface Forces 10.1 Short-range and long-range effects of a force Interaction potentials between macroscopic bodies Effective interaction area of two spheres: the Langbein 159 approximation 10.4 Interactions of large bodies compared to those between 159 molecules 10.5 Interaction energies and interaction forces: the Derjaguin 161 approximation 10.6 Experimental measurements of intermolecular and surface 165 forces 10.7 Direct measurements of surface and intermolecular forces 168 Chapter 11 van der Waals Forces Between Surfaces The force laws for bodies of different geometries: the 176 Hamaker constant 11.2 Strength of van der Waals forces between bodies in 178 vacuum or air 11.3 The Lifshitz theory of van der Waals forces Hamaker constants calculated on the basis of the Lifshitz 183 theory 11.5 Applications of the Lifshitz theory to interactions in a 188 medium 11.6 Repulsive van der Waals forces: disjoining pressure and 192 wetting films 11.7 Retardation effects Screened van der Waals forces in electrolyte solutions Combining relations Surface and adhesion energies Surface energies of metals Forces between surfaces with adsorbed layers Experiments on van der Waals forces 207 Chapter 12 Electrostatic Forces Between Surfaces in Liquids The charging of surfaces in liquids: the electric 'double 213 layer'

6 CONTENTS ix 12.2 Charged surfaces in water (no added electrolyte) The Poisson Boltzmann (PB) equation Surface charge, electric field and counterion concentration 217 at a surface 12.5 Counterion concentration profile away from a surface Origin of the ionic distribution, electric field, surface potential 221 and pressure 12.7 The pressure between two charged surfaces in water: the 223 contact value theorem 12.8 Limitations of the Poisson Boltzmann equation Thick wetting films Limit of small separations: charge regulation Charged surfaces in electrolyte solutions The Grahame equation Surface charge and potential in the presence of monovalent 234 ions Effect of divalent ions The Debye length Variation of potential and ionic concentrations away from 239 a charged surface The electrostatic double-layer interaction between charged 241 surfaces in electrolyte van der Waals and double-layer forces acting together: 246 the DLVO theory Experimental measurements of double-layer and DLVO 250 forces Effects of discrete surface charges and dipoles 254 Chapter 13 Solvation, Structural and Hydration Forces Non-DLVO forces Molecular ordering at surfaces and interfaces and in thin 261 films 13.3 Origin of main type of solvation force: the oscillatory force Measurements and properties of solvation forces: oscillatory 269 forces in non-aqueous liquids 13.5 Solvation forces in aqueous systems: repulsive 'hydration' 275 forces 13.6 Solvation forces in aqueous systems: attractive 'hydro- 282 phobic' forces Chapter 14 Steric and Fluctutation Forces Diffuse interfaces Polymers at surfaces 289

7 X CONTENTS 14.3 Repulsive 'steric' or 'overlap' forces between polymer- 293 covered surfaces 14.4 Forces in pure polymer liquids (polymer melts) Attractive 'intersegment,"bridging' and 'depletion' forces Non-equilibrium aspects of polymer interactions Thermal fluctuation forces between fluid-like surfaces Protrusion forces Undulation and peristaltic forces 307 Chapter 15 Adhesion Surface and interfacial energies Surface energies of small clusters and highly curved surfaces Contact angles and wetting films Hysteresis in contact angle and adhesion measurements Adhesion force between solid particles: the JKR and Hertz 326 theories 15.6 Effect of capillary condensation an adhesion 330 PART THREE Fluid-Like Structures and Self-Assembling Systems: Micelles, Bilayers and Biological Membranes Chapter 16 Thermodynamic Principles of Self-Assembly Introduction Fundamental thermodynamic equations of self-assembly Conditions necessary for the formation of aggregates Variation of pg, with N for simple structures of different 349 geometries: rods, discs and spheres 16.5 The critical micelle concentration (CMC) Infinite aggregates (phase separation) versus finite-sized 352 aggregates (micellization) 16.7 Size distributions of self-assembled structures More complex amphiphilic structures Effects of interactions between aggregates: mesophases and 362 multilayers Conclusion 364

8 CONTENTS xi Chapter 17 Aggregation of Amphiphilic Molecules into Micelles, 366 Bilayers, Vesicles and Biological Membranes 17.1 lntroduction: equilibrium considerations of amphiphilic 366 structures 17.2 Optimal headgroup area Ceometric packing considerations Spherical micelles Non-spherical and cylindrical micelles Bilayers Vesicles Factors affecting changes from one structure to another Curvature elasticity of bilayers and membranes Biological membranes Membrane lipids Membrane proteins and membrane structure 389 Chapter 18 The Interactions between Lipid Bilayers and Biological 395 Membranes 18.1 lntroduction Attractive van der Waals forces Electrostatic (double-layer) forces Hydration forces Limitations of the hydration mode) Steric forces Hydrophobic forces Specific interactions Interdependence of intermembrane and intramembrane 412 forces Adhesion Fusion 416 References 422 Index 437