A technical monograph on interfacial phenomena, co-authored with Raymond Defay
What the Work Is
Surface Tension and Adsorption is a scientific monograph co-authored by Ilya Prigogine and Raymond Defay, first published in 1966 by Longmans, Green & Co. Ltd. It is a technical work in physical chemistry, written in English, devoted to the thermodynamics of surfaces and the phenomenon of adsorption. The book belongs to Prigogine’s broader body of work in chemical thermodynamics, which also includes his earlier Chemical Thermodynamics (1954, with Defay) and Introduction to Thermodynamics of Irreversible Processes (1955).
What the Book Is About
The work addresses surface tension and adsorption — two closely related phenomena at the boundaries between phases. Surface tension is the tendency of a liquid surface to behave as though it were a stretched membrane, arising from the unbalanced forces experienced by molecules at an interface. Adsorption is the process by which atoms, ions, or molecules from a gas, liquid, or dissolved solid adhere to a surface. The book treats these topics within the framework of thermodynamics, examining how interfacial properties can be described and predicted using thermodynamic principles.
The subject matter connects to Prigogine’s lifelong research programme in thermodynamics, particularly his interest in systems that are not in equilibrium. Interfaces and adsorption processes are inherently non-equilibrium phenomena, and their rigorous thermodynamic treatment requires tools that go beyond classical equilibrium thermodynamics.
Key Ideas and Themes
The central concern of the book is the thermodynamic analysis of surfaces and interfaces. In classical thermodynamics, the bulk properties of a system are the primary focus; surfaces are treated as negligible or as simple boundaries. Surface Tension and Adsorption instead places the interface itself at the centre of analysis, treating it as a distinct phase with its own thermodynamic properties.
The concept of surface tension is fundamental to the book’s subject. At a liquid–gas interface, molecules at the surface experience different intermolecular forces than those in the bulk, because they have neighbours only on one side. This imbalance gives rise to a net inward force, which the surface resists by minimising its area — the effect we observe as surface tension. The book examines how this tension depends on temperature, composition, and the presence of dissolved substances.
Adsorption is the second major theme. When a solute accumulates at an interface rather than remaining uniformly distributed in the bulk, it is said to be adsorbed. The book explores the thermodynamic relationships that govern this accumulation, including how the concentration of a substance at a surface relates to its concentration in the adjacent bulk phase and to the surface tension of the system. These relationships are central to understanding phenomena such as the action of surfactants and the behaviour of thin films.
The work draws on the tradition of Gibbsian thermodynamics, in which the interface is treated as a mathematical dividing surface with excess quantities defined relative to the bulk phases. This approach allows the powerful machinery of classical thermodynamics — free energy, chemical potential, entropy — to be applied to interfacial systems. The book develops these ideas systematically, connecting fundamental theory to observable quantities.
Structure and Approach
The book is a technical monograph intended for researchers and advanced students in physical chemistry and chemical engineering. It presents its material through thermodynamic derivation and analysis rather than through experimental description alone. The approach is theoretical and mathematical, building on the foundations of classical thermodynamics and extending them to interfacial systems. As a co-authored work with Raymond Defay, it reflects a collaboration that also produced Chemical Thermodynamics in 1954.
Significance and Influence
Surface Tension and Adsorption forms part of Prigogine’s extensive contributions to thermodynamics, a body of work that culminated in his receipt of the 1977 Nobel Prize in Chemistry for his contributions to non-equilibrium thermodynamics, particularly the theory of dissipative structures. While the book itself predates his most celebrated work on self-organisation and irreversibility, it belongs to the same intellectual project: the extension of thermodynamic reasoning to phenomena that classical equilibrium theory handles poorly. The thermodynamics of surfaces and adsorption, like the thermodynamics of systems far from equilibrium, requires careful attention to how energy and matter are distributed and transferred in systems that are not uniform. The book thus represents an early and specialised application of Prigogine’s thermodynamic expertise to a domain of enduring importance in chemistry, materials science, and surface science.
Ilya Romanovich Prigogine was born in Moscow on 25 January (O.S. 12 January) 1917, a few months before the October Revolution, into a Jewish family. His father, Ruvim Abramovich Prigogine (1884–1974), was a chemist who had studied at the Imperial Moscow Technical School and owned a paint factory; his mother, Yulia Leivikovna Vikhman (1892–?), was a pianist who had attended the Moscow Conservatory. In 1921, after the factory was nationalized by the new Soviet regime and amid rising insecurity during the civil war, the family left Russia. Following a brief period in Lithuania, they settled in Berlin, Germany; eight years later, the poor economic situation and the creeping emergence of Nazism prompted a further move to Brussels, where Prigogine received Belgian nationality in 1949. His brother Alexandre (1913–1991) became an ornithologist.
As a teenager, Prigogine was interested in music, history and archeology, and he graduated from the Athénée d’Ixelles in 1935 with a major in Greek and Latin. His parents encouraged him toward a legal career, and he initially enrolled in law studies at the Free University of Brussels. During that period he developed an interest in psychology and the study of behaviour, which in turn triggered an interest in chemistry — since chemical processes impact the mind and body — and a more fundamental interest in physics, as it explains chemistry. He ultimately dropped out of the law faculty. He then enrolled simultaneously in chemistry and physics at the Free University of Brussels, achieving this with what has been described as “uncommon success”: he earned the equivalent of a Master’s degree in both disciplines in 1939, and a PhD in chemistry in 1941 under Théophile de Donder.
Career and Recognition
Prigogine began his research career under the German occupation of Belgium. From 1940 onward he gave clandestine lectures to students, and in 1941, when the university formally closed to protest the forced appointment of Flemish pro-Nazi New Order professors by the occupiers, he continued those clandestine lectures until the Liberation of Belgium in 1944. During that period he also published 21 articles. In 1943, Prigogine and his future wife Hélène Jofé were arrested by the Germans; after multiple interventions, including by the Queen Elisabeth, they were released a couple of weeks later.
In 1951 he became a full professor at his alma mater, and at 34 years old was the youngest ever full professor at the science faculty in Brussels. In 1959 he was appointed director of the International Solvay Institute in Brussels, and in that same year began teaching at the University of Texas at Austin, where he was later appointed Regental Professor and Ashbel Smith Professor of Physics and Chemical Engineering. From 1961 until 1966 he was affiliated with the Enrico Fermi Institute at the University of Chicago and was a visiting professor at Northwestern University. In Austin, in 1967, he co-founded the Center for Thermodynamics and Statistical Mechanics, now the Center for Complex Quantum Systems; that same year he returned to Belgium, where he became director of the Center for Statistical Mechanics and Thermodynamics.
He was a member of numerous scientific organizations and received numerous awards, prizes and 53 honorary degrees. In 1955 he was awarded the Francqui Prize for Exact Sciences; in 1976 he received the Rumford Medal for his study in irreversible thermodynamics; and in 1977 he received the Nobel Prize in Chemistry “for his contributions to non-equilibrium thermodynamics, particularly the theory of dissipative structures”. In 1989 he was awarded the title of viscount in the Belgian nobility by the King of the Belgians. Until his death he was president of the International Academy of Science, Munich, and in 1997 was one of the founders of the International Commission on Distance Education (CODE), a worldwide accreditation agency. He received an Honorary Doctorate from Heriot-Watt University in 1985, and in 1998 was awarded an honoris causa doctorate by the UNAM in Mexico City.
Prigogine was first married to Belgian poet Hélène Jofé (also known as Hélène Prigogine), and in 1945 they had a son, Yves. After their divorce, he married Polish-born chemist Maria Prokopowicz (also known as Maria Prigogine) in 1961; in 1970 they had a son, Pascal. In 2003 he was one of 22 Nobel Laureates who signed the Humanist Manifesto. He died on 28 May 2003.
Research Beyond the Book
Prigogine defined dissipative structures and their role in thermodynamic systems far from equilibrium, the discovery that won him the Nobel Prize in Chemistry in 1977. In summary, he discovered that importation and dissipation of energy into chemical systems could result in the emergence of new structures — hence dissipative structures — due to internal self-reorganization. In his 1955 text, Prigogine drew connections between dissipative structures and the Rayleigh-Bénard instability and the Turing mechanism, and his 1977 work on self-reorganization was recognized as relevant for psychology.
Dissipative structure theory led to pioneering research in self-organizing systems, as well as philosophical inquiries into the formation of complexity in biological entities and the quest for a creative and irreversible role of time in the natural sciences. With professor Robert Herman, Prigogine also developed the basis of the two fluid model, a traffic model in traffic engineering for urban networks, analogous to the two fluid model in classical statistical mechanics — a common problem that had attracted his attention some years before. His formal concept of self-organization was also used as a “complementary bridge” between general systems theory and thermodynamics, conciliating the cloudiness of some important systems theory concepts such as entropy instead of molecular disorder, and emergence, fluctuations and irreversibility instead of “birth and death”, with scientific rigor.
In his later years, his work concentrated on the fundamental role of indeterminism in nonlinear systems on both the classical and quantum level. Prigogine and coworkers proposed a Liouville space extension of quantum mechanics. A Liouville space is the vector space formed by the set of (self-adjoint) linear operators, equipped with an inner product, that act on a Hilbert space. There exists a mapping of each linear operator into Liouville space, yet not every self-adjoint operator of Liouville space has a counterpart in Hilbert space, and in this sense Liouville space has a richer structure than Hilbert space. The Liouville space extension proposal by Prigogine and co-workers aimed to solve the arrow of time problem of thermodynamics and the measurement problem of quantum mechanics. Prigogine co-authored several books with Isabelle Stengers, including The End of Certainty and La Nouvelle Alliance (Order Out of Chaos: Man’s New Dialogue with Nature).
The End of Certainty
In his 1996 book La Fin des certitudes, written in collaboration with Isabelle Stengers and published in English in 1997 as The End of Certainty: Time, Chaos, and the New Laws of Nature, Prigogine contends that determinism is no longer a viable scientific belief: “The more we know about our universe, the more difficult it becomes to believe in determinism.” This is a major departure from the approach of Newton, Einstein and Schrödinger, all of whom expressed their theories in terms of deterministic equations. According to Prigogine, determinism loses its explanatory power in the face of irreversibility and instability.
Prigogine traces the dispute over determinism back to Darwin, whose attempt to explain individual variability according to evolving populations inspired Ludwig Boltzmann to explain the behavior of gases in terms of populations of particles rather than individual particles. This led to the field of statistical mechanics and the realization that gases undergo irreversible processes. In deterministic physics, all processes are time-reversible, meaning that they can proceed backward as well as forward through time. As Prigogine explains, determinism is fundamentally a denial of the arrow of time. With no arrow of time, there is no longer a privileged moment known as the “present,” which follows a determined “past” and precedes an undetermined “future.” All of time is simply given, with the future as determined or as undetermined as the past. With irreversibility, the arrow of time is reintroduced to physics. Prigogine notes numerous examples of irreversibility, including diffusion, radioactive decay, solar radiation, weather and the emergence and evolution of life. Like weather systems, organisms are unstable systems existing far from thermodynamic equilibrium. Instability resists standard deterministic explanation. Instead, due to sensitivity to initial conditions, unstable systems can only be explained statistically, that is, in terms of probability.
Prigogine asserts that Newtonian physics has now been “extended” three times: first with the introduction of spacetime in general relativity, then with the use of the wave function in quantum mechanics, and finally with the recognition of indeterminism in the study of unstable systems (chaos theory).
Other Publications
Beyond Surface Tension and Adsorption, Prigogine’s published works include Chemical Thermodynamics (1954, with R. Defay; London: Longmans Green and Co.); Introduction to Thermodynamics of Irreversible Processes (1955, Springfield, Illinois: Charles C. Thomas Publisher; a second edition appeared in 1961 with Interscience, New York); The Molecular Theory of Solutions (1957, Amsterdam: North Holland Publishing Company); Non-equilibrium Statistical Mechanics (1962, Monographs in Statistical Physics and Thermodynamics, Vol. I, Interscience Publishers; reprinted in 2017 by Courier Dover Publications); Thermodynamics Theory of Structure, Stability and Fluctuations (1971, with Paul Glansdorff; London: Wiley-Interscience); Kinetic Theory of Vehicular Traffic (1971, with R. Herman; New York: American Elsevier); Self-Organization in Non-Equilibrium Systems (1977, with G. Nicolis; Wiley); From Being To Becoming (1980, Freeman); Order out of Chaos: Man’s new dialogue with nature (1984, with Isabelle Stengers; Flamingo; a 2018 edition was published by Verso Books); Exploring Complexity: An Introduction (1989, with G. Nicolis; New York, NY: W. H. Freeman); Chaotic Dynamics and Transport in Fluids and Plasmas: Research Trends in Physics Series (1993, New York: American Institute of Physics); Modern Thermodynamics: From Heat Engines to Dissipative Structures (1998, with Dilip Kondepudi; Wiley; a 2014 edition was published by John Wiley & Sons); and Is future given? (2003, World Scientific). He also produced United States Department of Energy progress reports on The Behavior of Matter under Nonequilibrium Conditions: Fundamental Aspects and Applications in Energy-oriented Problems, and the paper “Time, Dynamics and Chaos: Integrating Poincare’s ‘Non-Integrable Systems'” (October 1990). With T. Petrosky he published The Liouville space extension of quantum mechanics in Advances in Chemical Physics (1997, vol. 99, pp. 1–120). He was an editor, with Stuart A. Rice, of the Advances in Chemical Physics book series published by John Wiley & Sons, which presently runs to over 140 volumes.
The Ilya Prigogine Prize for Thermodynamics
The Ilya Prigogine Prize for Thermodynamics was initialized in 2001 and patronized by Ilya Prigogine himself until his death in 2003. It is awarded on a biennial basis during the Joint European Thermodynamics Conference (JETC) and considers all branches of thermodynamics — applied, theoretical, and experimental as well as quantum thermodynamics and classical thermodynamics.
