Thermodynamics of surfaces

The work of adhesion W is the work to generate a new surface. The work of adhesion is related to the free energy by the Dupr equation. If a joint is peeled, a certain surface A is lost and but another surface is created. 

There is a relationship between the contact angles of certain liquids (L) to solid bodies (S) and adhesives that are chemically related to the liquids. 

The contact angle (p is related to the surface tension in the equilibrium of forces as 

The critical surface tension of a material can be determined from a Zisman plot (3), which measures the variation in the contact angle as a function of the surface tension of a series of liquids. 

Zisman noticed empirically that a plot of cos p versus ol,v is often linear. The value for which cos (p extrapolates to 1 is termed as the critical surface tension. From this empirical experience the following equation arises  

In this chapter, we discuss the thermodynamic properties of surface phases. In the previous chapters we have assumed that heterogeneous systems consist of a number of completely homogeneous phases separated by sharply defined mathematical surfaces. It is clear from either molecular or macroscopic considerations that this assumption cannot rigorously apply. Molecules in the vicinity of the interface between any two phases experience a different environment from molecules in the bulk of the phases. Thus, the densities of the various components and the densities of energy and entropy in the vicinity of the interface will be different from the corresponding densities in the bulk phases. However, the influence of the interface does not extend for more than a few molecular dimensions (about 10 cm) into the phases, and the phases may therefore be assumed to be uniform except in the immediate neighborhood of the interfaces. The interface between two phases is in reality a thin region in which the physical properties vary continuously from the bulk properties of one phase to the bulk properties of the other phase. 

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Figure III-l depicts a hypothetical system consisting of some liquid that fills a box having a sliding cover the material of the cover is such that the interfacial tension between it and the liquid is zero. If the cover is slid back so as to uncover an amount of surface dJl, the work required to do so will he ydSl. This is reversible work at constant pressure and temperature and thus gives the increase in free energy of the system (see Section XVII-12 for a more detailed discussion of the thermodynamics of surfaces).

S. A. Sairan, Statistical Thermodynamics of Surfaces, Interfaces and Membranes, Addison-Wesley, Reading, MA, 1994. 

S. Ross and I. D. Morrison, Colloidal Systems and Interfaces, Wiley, New York, 1988. S. A. Saffan, Statistical Thermodynamics of Surfaces, Interfaces and Membranes, Addison-Wesley, Reading, MA, 1994. 

Thermodynamics of Surface Systems (Eriksson) Towards an Analytic Theory of Chemical Reactions 6 145... 

As in so many other fundamental aspects of the thermodynamics of surfaces, we are indebted to Gibbs 6) for pointing out that for solids the surface tension (7) and surface free energy (F ) are not equivalent quantities. Nevertheless, as Shuttleworth (7) mentions in an excellent review, the two terms have been (8) and still are (9) confused. The relationship between the quantities is... 

If one adds an inorganic salt, such as NaCl, instead of detergent, then no foam is formed. Foam formation indicates that the surface-active agent adsorbs at the surface, and forms a TLF (consisting of two layers of amphiphile molecules and some water). This has led to many theoretical analyses of surfactant concentration (in the bulk phase) and surface tension (consequent on the presence of surfactant molecules at the surface). The thermodynamics of surface adsorption has been extensively described by the Gibbs adsorption theory (Chattoraj and Birdi, 1984). 

THERMODYNAMICS OF SURFACES SURFACE TENSION AS SURFACE FREE ENERGY... 

Somorjai, G. A., Introduction to Surf ace Chemistry and Catalysis, Wiley, New York, 1994. (Undergraduate level. This in-depth treatment of surface chemistry and catalysis brings the experience and perspectives of a pioneer in the field to the general audience. The book is meant to be an introductory-level description of modern developments in the area for students at the junior level. However, it is also an excellent source of the current literature and contains numerous, extensive tables of data on kinetic parameters, surface structure of catalysts, and so on. Chapter 3, Thermodynamics of Surfaces, and Chapter 7, Catalysis by Surfaces, cover information relevant to the present chapter. Chapter 8 discusses applications in tribology and lubrication (not discussed in this chapter).)... 

J.M. Blakely. Thermodynamics of surfaces and interfaces. In M.B. Bever, editor, Encyclopedia of Materials Science and Engineering, pages 4962-4967. Pergamon Press, New York, 1986. 

F.C. Frank. The geometrical thermodynamics of surfaces. In W.D. Robertson and N.A. Gjostein, editors, Metal Surfaces, pages 1-15. American Society for Metals, Metals Park, OH, 1963. 

Warren. W.S.. Rahi/.. L. und M. Daldeh "Coherent Control of Quantum Dynamics Tlie Dream is Alive." Seienee. 1581 (March 12. I99JE Williams. E.D. and N. C Bartelt- "Thermodynamics of Surface Morphology." Seiertt e. 393 (January 25. 19911... 

Williams, E.D. and N.C. Baitelt Thermodynamics of Surface Morphology, Science, 393 (January 25, 1991). 

Surface effects are negligible in many cases. However, when the surface-to-volume ratio of the system is large, surface effects may become appreciable. Moreover, there are phenomena associated with surfaces that are important in themselves. Only an introduction to the thermodynamics of surfaces can be given here, and the discussion is limited to fluid phases and the surfaces between such phases. Thus, consideration of solid-fluid interfaces are omitted, although the basic equations that are developed are applicable to such interfaces provided that the specific face of the crystal is designated. Also, the thermodynamic properties of films are omitted. 

Gibbs s adsorption equation. Guggenheim,2 developing some considerations put forward by Verschaffelt, has worked out the thermodynamics of surfaces, using a conception of the surface layer which is much more easily visualized physically than that used by Gibbs. Gibbs s surface excess is a very difficult quantity to interpret physically, as it is... 

The thermodynamics of a drop of liquid is comparatively simple. Surface tension produces a pressure which increases the partial molar free energy at any point within the drop. The escaping tendencies of material within the drop and of material in its surface are thus equalized. Considerations of this equilibrium have been recognized as fundamental in classic discussions of the thermodynamics of surface tension (18) and in investigations of pressures within, and the shapes of, bubbles and drops (2, 22). 

Capillarity — (a) as a branch of science, it concerns the thermodynamics of surfaces and - interfaces. It is of utmost importance for - electrochemistry, e.g., treating the electrode solution interface (- electrode, - solution), and it extends to several other branches of physics, chemistry, and technical sciences [i]. The thermodynamic theory of capillarity goes back to the work of Gibbs, (b) In a practical sense capillarity means the rise or fall of a liquid column in a capillary caused by the interplay of gravity and -> interfacial tension and also phenomena like capillary condensation [ii]. 

When the thermodynamics of surfaces are discussed in terms of excess quantities relative to a Gibbs surface, there is only one way of defining the excess enthalpy, that is, these quantities depend on (y, /4,) but not on (p, V) because... 

S. S. Safran, Statistical Thermodynamics of Surfaces, Interfaces, and Membranes, Addlson-Wesley (1994). (Interpretation of interfacial tensions, capillarity further reading to sec. 4.7.)... 

J.M. Sanchez, J.L. Moran-Lopez, Statistical Thermodynamics of Surfaces and Interfaces, in Nanophases and Nanocrystalline Structures, R.D. Shull and J.M, Sanchez Eds., A publication of TMS, Warrendale, Pennsylvania, 1993. 

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