Electrostatics, Hydration, and Chemical Equilibria at Charged Monolayers on Water

The chemistry and physics of soft matter interfaces, especially aqueous-organic interfaces, are centrally important to many areas of science and technology. Often, the thermodynamics, kinetics, and selectivity of reactions are modified at interfaces. Here, we review the electrostatics and hydration at charged monolayers on water and their influence on interfacial chemical equilibria. First, we provide an understanding of interfaces as a conceptual continuation of the solvation shell of small molecules, along with recent relevant experimental work. Then, we provide a summary of models for describing the electrostatics of aqueous interfaces. While we will discuss a range of new developments, our focus will be on systems where the electrostatics of the surface is controllable by the choice of relatively simple insoluble surfactants. New insights into the molecular structure of the double layer, with particular attention on the knowledge gained from spectroscopy will be reviewed. Our approach is to familiarize the reader with simple models, followed by discussion of models with further complexity for explaining interfacial phenomena. Experiments that test the limits of such models will also be discussed. Finally, we will provide an outlook on engineering the interfacial environment for tailored reactivity, along with the anticipated experimental advancements and potentials impacts.