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Molecular theory of capillarity (international series of monographs in chemistry, vol. 8)
Fluid Phase Equilibria, 16 (1984) 237-238 Elsevier Science Publishers B.V.. Amsterdam
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Printed in The Netherlands
Book Review Molecular Theory of Capillarity (International Series of Monographs in Chemistry, Vol. 8), by J.S. Rowlinson and B. Widom, Oxford University Press,
Oxford, 1982, 327 pp., ISBN O-19-855612-8. The phenomena of tension, wetting, contact angle, drop behaviour, etc. that occur at the surface of a liquid have interested scientists for centuries, but it is only recently that rigorous theories of such behaviour have begun to emerge. The work of the early 19th century, due to such men as Laplace and Young, was based on mechanical models of the interface. Much of the later work has made use of quasithermodynamic theories, and has been strongly influenced by the studies of Gibbs and van der Waals. The quasithermodynamic approach to surface properties is based on the idea that it is possible to define local values of the intensive thermodynamic properties in the interface. Although such a concept is questionable, because the range of inhomogeneity is often of the same order as that of the intermolecular forces, these theories have been remarkably successful and continue to be valuable when used correctly. However, they do not provide a direct link between observable properties and the underlying intermolecular forces. For this it is necessary to turn to statistical mechanics. There has been a great surge of interest in the last five years or so in applying statistical mechanics to surface phenomena. Much progress has been made, but a number of points of controversy still exist: for example, the presence or otherwise of an intrinsic surface in the absence of gravity, the nature of wetting phase transitions, the behaviour of small drops, etc. This is a very active research area. The book by Rowlinson and Widom gives an admirable account of all three approaches to the liquid surface. The first chapter describes the early work of Laplace, Young and others, using mechanical models. This is followed by chapters on the classical thermodynamics of surfaces and the quasithermodynamic theory of van der Waals. The fourth chapter is the longest in the book, and gives a detailed account of the statistical mechanics of the interfacial region; topics include the pressure tensor, various routes to the surface tension, the functional approach, the spherical surface, and the validity of the quasithermodynamic approach. The next three chapters build on this statistical-mechanical base, and cover model fluids (lattice-gas and penetrable spheres) in the mean-field approximation, computer simulation studies, and approximate statistical-mechanical theories (integral equation
238
and perturbation theory). This is followed by a discussion of three-phase equilibria, including contact angles, spreading and interfacial phase transitions, and by a final chapter on interfaces near critical points. The main emphasis of the book is on the gas-liquid interface, although there is some discussion of the liquid-liquid interface, and many of the basic equations will apply to interfaces in general. Rowlinson and Widom have made major contributions to this field, and their book will be the authoritative one on this subject. KEITH
E. GUBBINS
237 -
Printed in The Netherlands
Book Review Molecular Theory of Capillarity (International Series of Monographs in Chemistry, Vol. 8), by J.S. Rowlinson and B. Widom, Oxford University Press,
Oxford, 1982, 327 pp., ISBN O-19-855612-8. The phenomena of tension, wetting, contact angle, drop behaviour, etc. that occur at the surface of a liquid have interested scientists for centuries, but it is only recently that rigorous theories of such behaviour have begun to emerge. The work of the early 19th century, due to such men as Laplace and Young, was based on mechanical models of the interface. Much of the later work has made use of quasithermodynamic theories, and has been strongly influenced by the studies of Gibbs and van der Waals. The quasithermodynamic approach to surface properties is based on the idea that it is possible to define local values of the intensive thermodynamic properties in the interface. Although such a concept is questionable, because the range of inhomogeneity is often of the same order as that of the intermolecular forces, these theories have been remarkably successful and continue to be valuable when used correctly. However, they do not provide a direct link between observable properties and the underlying intermolecular forces. For this it is necessary to turn to statistical mechanics. There has been a great surge of interest in the last five years or so in applying statistical mechanics to surface phenomena. Much progress has been made, but a number of points of controversy still exist: for example, the presence or otherwise of an intrinsic surface in the absence of gravity, the nature of wetting phase transitions, the behaviour of small drops, etc. This is a very active research area. The book by Rowlinson and Widom gives an admirable account of all three approaches to the liquid surface. The first chapter describes the early work of Laplace, Young and others, using mechanical models. This is followed by chapters on the classical thermodynamics of surfaces and the quasithermodynamic theory of van der Waals. The fourth chapter is the longest in the book, and gives a detailed account of the statistical mechanics of the interfacial region; topics include the pressure tensor, various routes to the surface tension, the functional approach, the spherical surface, and the validity of the quasithermodynamic approach. The next three chapters build on this statistical-mechanical base, and cover model fluids (lattice-gas and penetrable spheres) in the mean-field approximation, computer simulation studies, and approximate statistical-mechanical theories (integral equation
238
and perturbation theory). This is followed by a discussion of three-phase equilibria, including contact angles, spreading and interfacial phase transitions, and by a final chapter on interfaces near critical points. The main emphasis of the book is on the gas-liquid interface, although there is some discussion of the liquid-liquid interface, and many of the basic equations will apply to interfaces in general. Rowlinson and Widom have made major contributions to this field, and their book will be the authoritative one on this subject. KEITH
E. GUBBINS