ABSTRACT
I. INTRODUCTION A. Aims of the Chapter The impetus for development of a method for determining interfacial compositions of surfactant assemblies based on the chemistry of arenediazonium ions came from several directions: (1) Most current methods for estimating the compositions of surfactant aggregates are based on physical methods that monitor only one component at a time [1]. (2) The understanding of chemical reactivity in surfactant assemblies in terms of pseudophase models developed to the point that they provide consistent qualitative and often quantitative interpretations of surfactant assembly effects on rate and equilibrium constants of chemical reactions [2-6]. (3) I sought an experimental method to answer a deceptively simple question: how can interfacial concentrations and distributions of two similar inorganic anions, e.g., Cl and Br, between cationic micelles and water be measured simultaneously? Ions bind selectively to interfacial regions of aggregates, but because of interferences, physical methods often cannot discriminate between two similar ions in the same solution. Chemical trapping discriminates between these and a variety of other anions. But it does much more. It also provides simultaneous estimates of their concentrations and that of water within the interfacial region over wide ranges of surfactant and counterion concentrations. Research over the past decade shows that the method has broad
general utility because it works with both anionic and neutral nucleophiles and because it provides estimates of the distributions of nucleophiles between the oilinterfacial and water-interfacial regions of microemulsions. The method has the potential to provide information on interfacial concentrations of many of the important functional groups present in biological membranes and in commercial surfactant-based products.
