Book Review: Emulsions: From Single Interfaces to Applications; Miller, R., Guzmán-Solís, E., Eds.; CRC Press: Boca Raton, FL, USA, 2025; ISBN: 978-1-032-63610-8

Volume 8 of the book series ‘Progress in Colloid and Interface Science’ is dedicated to emulsions and their building blocks, the adsorption layers at the surface of emulsion drops and the liquid films between the drops. Besides the fundamentals of colloid and interface science providing the basis for understanding emulsions, a large part of the book is dedicated to practical systems. Also, quite a large number of modern technologies are analyzed, for example, those relevant for enhanced oil recovery or the production and application of pesticides or biomedicines. Knowledge of the physicochemical aspects of the involved liquid interfacial layers and liquid films allows us to better increase and control the stability of emulsions as their most important property.

Section I, consisting of six chapters, comprises all information required to understand the rather multifaceted world of emulsions. It starts with a quite general introduction to liquid interfaces, including the basic thermodynamics of interfacial layers, as well as the dynamics of their formation. Chapter 2 describes in detail the adsorption of surfactants, polymers and proteins in terms of adsorption isotherms and equations of state. Moreover, the partition coefficient, as an essential parameter of water/oil systems, is discussed. Also, the most recent peculiarity of adsorption layers, i.e., the fact that the oil molecules are also part of the mixed interfacial layers, is described in more detail. Subsequently, Chapter 3 very carefully describes experimental methods for determining the key parameters of liquid/fluid interfaces. This includes, in particular, drop profile tensiometry as the work horse for these types of interfaces, as well as interfacial ellipsometry and X-ray and neutron reflectometry. Chapter 4 describes all facets of particle-laden interfaces and their importance in the formation and stabilization of Pickering emulsions. This includes the wettability of micro- and nanoparticles and their modification by added surfactants. Chapter 5 provides the present view on how interfacial properties are linked to the behavior of produced emulsions, while Chapter 6 discusses in more detail the role of the intermediate building blocks of emulsions, i.e., emulsion films. The properties of emulsion films and their role in stabilizing emulsions is an often-ignored aspect.

Section II of this book consists of five chapters dedicated to the preparation and characterization of emulsions. Chapter 7 describes experimental methods suitable for producing emulsions, starting with a simple stirring protocol and finishing with high-pressure micro-fluidization. This chapter also discussed spontaneous emulsification, as well as phase inversion processes. The formation of microemulsions and the partitioning of surfactants in water/oil systems is the subject of Chapter 8. Chapter 9 deals with Pickering emulsions and shows the remarkable differences between emulsion systems stabilized by surfactants and polymers. Chapter 10 summarizes recent advances in controlling the stability of emulsions, and, finally, Chapter 11 discusses the case of water-in-water emulsions. Due to coacervation and segregation, a phase separation occurs, for example, in mixed aqueous solutions of different polymers.

The three chapters of Section III are dedicated to the description of important fields of application for emulsions. As demonstrated in Chapter 12 in some detail, emulsions are the obvious systems used in the petroleum industry. The particular role of asphaltenes as surface-active substances found in crude oils is discussed with regard to components that influence the stability of the various types of emulsions found in such systems, i.e., W/O and O/W, as well as O/W/O and W/O/W multiple emulsions. The structure and surface activity of the present asphaltenes vary from one reservoir to another and even within a single reservoir. Chapter 13 describes the important role of emulsions in pest control, as most of the available pesticides are water-insoluble and can therefore only be administered in the form of emulsions. Finally, Chapter 14 is dedicated to applications of usual and multiple emulsions in the broad field of pharmacy.

Each chapter contains a balanced list of the most relevant references, including historical, as well as the most recent, publications. The final joint subject index at the end of the book gives links to keywords in all chapters. The book also provides respective detailed descriptions of all figures in the book so that they can be appreciated audibly.

The editors of this book on emulsions are Reinhard Miller and Eduardo Guzmán, who are also the present editors of the whole book series published with CRC Press. Both are well known in the field of fluid interfaces. While Miller is an expert in the domain of the thermodynamics, kinetics and visco-elasticity of surfactants and protein adsorption layers at liquid interfaces, Guzmán works intensively and successfully on the impact of nanoparticles and polymers on the interfacial properties of complex systems, for example, those mimicking the behavior of pulmonary surfactants. The teams of co-authors for the 14 chapters comprise experts from several countries in Europe, North America and South America, as well as from Australia. This consortium of experts is a guarantee that this is a book of very high quality.

In summary, this book will be considerably informative not only for students but also for experts in the field. I recommend this book to all who want to be updated about the fundamental and applied aspects of emulsion systems, which also include the most recent details of the building blocks of emulsions—the adsorption layers at water/oil interfaces and liquid oil-in-water or water-in-oil emulsion films.