Thermodynamics of Surfaces and Interfaces

There are numerous physical changes as well. The orientation of the polymer at the surface is almost always different from the interior. The polymer chains may be lying flat, oriented in the surface plane, or if some special group (especially a group at the end of the chain) is attracted to the surface, the orientation of adjacent mers may be normal to the surface plane. In such cases, of course, the concentration of the special group will be higher at the surface than in the interior. 

According to Dee and Sauer (5,6), the interfacial width between a bulk polymer melt and pure air (assuming the vapor pressure of the polymer is negligible) is of the order of 10 to 15 A. There are two aspects to be considered. First, the depth of the surface of interest depends on the nature of the quantity being studied. Second, the measurable thickness depends on the instrument being used. Both of these aspects will be discussed in the following sections. 

The inhomogeneous organization of the atoms at the surface of a condensed phase causes the phenomenon known as surface tension, y.The surface tension is the reversible work needed to create a unit surface area in a substance. The idea of surface tension goes back to the concept that the surface of a Uquid has some kind of contractile skin. The surface tension is sometimes called the specific surface energy, the intrinsic surface energy, or the true surface energy. Surface tension has the cgs units of ergs/cm or SI units of J/ml However, since work can be expressed as force times distance, the units are sometimes expressed as dyn/cm or N/m. 

Just as gases, liquids, and solids have thermodynamic properties, so do surfaces and interfaces. The work, W, required to create a unit of surface area, dA, is expressed by 

The change in the free energy of a surface, dG, on incrementing the area by dA is also given by 

---

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. 

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]. 

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. 

An accessible yet rigorous discussion of the thermodynamics of surfaces and interfaces, bridging the gap between textbooks and advanced literature by delivering a comprehensive guide without an overwhelming amount of mathematics. 

Thermodynamics of surfaces and interfaces concepts in inorganic materials / Gerald H. Meier, University of Pittsburgh, pages cm... 

S Safran, Statistical Thermodynamics of Surfaces and Interfaces. New York Addi-... 

The purpose of this chapter is to introduce the effect of surfaces and interfaces on the thermodynamics of materials. While interface is a general term used for solid-solid, solid-liquid, liquid-liquid, solid-gas and liquid-gas boundaries, surface is the term normally used for the two latter types of phase boundary. The thermodynamic theory of interfaces between isotropic phases were first formulated by Gibbs [1], The treatment of such systems is based on the definition of an isotropic surface tension, cr, which is an excess surface stress per unit surface area. The Gibbs surface model for fluid surfaces is presented in Section 6.1 along with the derivation of the equilibrium conditions for curved interfaces, the Laplace equation. 

Rosenholm, J. B. (2007), Wetting of surfaces and interfaces A conceptual equilibrium thermodynamic approach, in Colloid Stability The Role of Surface Forces, Part II,Tharwat F. Tadros Colloids and Interface Science Series, Vol. 2, Wiley-VCH, Weinheim. 

The Physical Methods of Chemistiy is a multivolume series that includes Components of Scientific Instruments (Vol. I), Electrochemical Methods (Vol. II), Determination of Chemical Composition and Molecular Structure (Vol. Ill), Microscopy (Vol. IV), Determination of Structural Features of Crystalline and Amphorous Solids (Vol. V), Determination of Thermodynamic Properties (Vol. VI), Determination of Elastic and Mechanical Properties (Vol. VII), Determination of Electronic and Optical Properties (Vol. VIII), Investigations of Surfaces and Interfaces (Vol. IX), and Supplement and Cumulative Index (Vol. X). 

This journal publishes new and original experimental and theoretical basic research directed toward researchers in materials, interfaces, and biophysical chemistry. Coverage includes new findings and full-length studies of physical chemistry of materials from nanoparticles to macromolecules physical chemistry of surfaces and interfaces statistical mechanics and thermodynamics of condensed matter and biophysical chemistry. Invited papers review the status of a particular topic, clarify controversies, or explore future directions. Proceedings of selected symposia and special thematic issues appear throughout the year. Rapid publications of urgent and new results appear in the Letters section. 

The purpose of this book is to describe the present state of development of modem surface science at an introductory level to students of physical sciences and engineering. Junior standing in chemistry, physics, engineering, or the life sciences would qualify the student to take a course that would make use of this text. Teachers of introductory general chemistry courses usually given during the first year of university or college enrollment could use certain chapters (with deletions of some of the derivations) to supplement discussions of thermodynamics or catalysis, for example. We have used some of the chapters as supplementary material in our freshman and our core physical chemistry courses at Berkeley. The book should also be useful as a reference for professionals in need of data and concepts related to the properties of surfaces and interfaces. 

Journal of Physical Chemistry B. - The Journal of Physical Chemistry B publishes studies on materials (e.g. nanostructures, micelles, macromolecules, statistical mechanics and thermodynamics of condensed matter, biophysieal chemistry, and general physical chemistry), as well as studies on the structure and properties of surfaces and interfaces. 

Since atoms or molecules in the vicinity of the surface of a condensed phase have different bonding from those in the hulk they have different thermodynamic properties. In this chapter the concept of the Gibbs dividing surface and the two fundamental quantities for describing the thermodynamic properties of surfaces and interfaces, surface energy (y) and surface stress (a ), are defined. The relations between y and the other thermodynamic variables for surfaces are established. Finally, methods for obtaining y and cr are described and representative values of both are presented. 

In this chapter the structure and thermodynamics of the various interfaces which can form between different phases in sohd systems are described. Essentially, all tbe features described in Chapter 4 for single-phase systems apply, with added complexity being introduced by differences in crystal structure and/or composition of the adjoining phases. Particular emphasis is placed on the effects of surfaces and interfaces on chemical reactions involving thin films. 

The book begins with a review of the relevant aspects of the thermodynamics of bulk systems (Chapter 1). It then includes a description of the thermodynamic variables employed to describe the behavior of surfaces and interfaces (Chapter 2). In this chapter the distinction between surface energy and surface stress is made. Then important surface phenomena are described. These include wetting (Chapter 3), surfaces and interfaces in crystalline systems, including grain boundaries (Chapter 4), interfaces between different phases (Chapter 5), curved interfaces (Chapter 6), adsorption phenomena (Chapter 7) and adhesion of surface layers (Chapter 8). The later chapters also contain case studies to illustrate the application of the concepts that are developed. Each of the chapters contains a set of study problems to reinforce the reader s understanding of important concepts. 

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. 

---