Surface and Colloid Science

Cetyl alcohol is one of the important components in various preparations, such as cosmetic creams or lotions, or pharmaceutical hydrophilic ointments. Sometime ago a curious phenomenon was observed, namely, the cream was unstable when prepared with 1-hexadecanol instead of cetyl alcohol. This finding triggered studies on the difference between 1-hexadecanol and cetyl alcohol by many workers, including the authors of this review.

Binding of ions to various materials, such as small molecules, proteins, polymers, colloid particles, and membranes, represents a central theme in basic and applied chemistry. Particularly, the case of proton binding to these substances (i.e., their acid-base behavior) has been a focus of research in many branches of chemistry since the turn of the century. One important topic in physical, analytical, and inorganic chemistry is the measurement, compilation, and prediction of acid-base properties of simple molecules or solvated metal ions.^(1–8) These topics remain of much relevance for the development of new analytical techniques and tailoring of buffering or complexing agents.^(7,9) Accurately known ionization constants also represent a rather stringent testing ground of our ab initio simulation capabilities of simple molecules in water.⁽¹⁰⁾ Acid-base properties of proteins have been also investigated from early on.^(11–14) This field has now matured into an active area of modern biochemistry with implications to the current view of protein folding, enzyme action, and photosynthesis.^(15–17) Similar studies of weak polyelectrolytes were initiated in polymer science almost simultaneously^(18–21) These systems represent an ongoing challenge to our understanding of acid-base equilibria.^(22–25) The substantial interest in polyelectrolytes is due to their use as complexing, flocculating, or stabilizing agents, and their importance in various applications in catalysis, material engineering, biochemistry, and water purification.^(26–28)

The entire array of charged species and oriented dipoles existing at the electrode/electrolyte interface, i.e., the structure of the electrical double layer, can have predominant effects on electrode processes. Several, now classic, books (see e.g., Refs. 1–3) have presented a description and analysis of the structure of the electrical double layer, emphasizing the central role of two types of adsorption (such as specific and nonspecific) in the understanding and mechanistic interpretation of various interfacial phenomena. Owing to the potential relevance of this field, comprehensive investigations of the sorption processes occurring at electrode/electrolyte (especially at metal/solution) heterogeneous systems have comprised a substantial part of electrochemical studies for many decades. Extended fundamental and applied research has been carried out on various, more or less closely related topics. In addition to an examination of the adsorption, electrosorption, electrocata-lytic, etc., behavior of different metal (mainly noble metal) electrodes, studies into the kinetics and mechanisms of corrosion, corrosion inhibition, and radioactive contamination processes on metallic constructional materials of industrial importance have also entered the spotlight of scientific interest (see Refs. 3–8 and references cited therein).