Acid—base interfacial interactions in aqueous media

The role of electron-acceptor—electron-donor, i.e. Lewis acid—base (AB) interfacial interactions in polar media, especially in aqueous media, is reviewed, together with the role of interfacial Lifshitz—van der Waals (LW) interactions, which, although often relatively weak, are always present. The methodology of measurement of AB (concomitantly with LW) surface tension components and parameters is discussed, together with the development of earlier AB concepts. Also discussed are the following: AB interactions as driving force for “hydrophobic” attractions, and for hydrophilic (“hydration force”) repulsions; use of AB free energies in energy balance studies of the stability (or flocculation) of particle suspensions; role of AB forces in the aqueous solubility of polymers, surfactants and other solutes; AB repulsions in aqueous polymer phase separation, microemulsion formation, advancing freezing front interactions, and coacervation. Finally, the role of AB free energies of interaction in aqueous adsorption and adhesion phenomena is treated, including applications to protein adsorption, various modes of liquid chromatography, cell adhesion and cell—cell interactions, and in specific interactions such as antigen—antibody, lectin—carbohydrate, enzyme—substrate and ligand—receptor combinations. The review ends with a summary of the salient and novel aspects of AB interfacial interactions.