Towards the determination of partition coefficients of cosurfactants at surfactant bilayer interfaces by muon spin resonance spectroscopy

Abstract

Avoided level crossing muon spin resonance (ALC-μSR) studies on the muonated cyclohexadienyl radical derived from the amphiphilic cosurfactant 2-phenylethanol have been used to derive cosurfactant partitioning and local environment information when dispersed in a concentrated lamellar phase dispersion. The study of partitioning at the bilayer/water interface at high surfactant concentrations is technically difficult and has consequently received very little attention. Calibration of the working range of fundamental resonance positions facilitates direct determination of cosurfactant partitioning with respect to the oil/water environment. Additional resonances yield other information about the local environment such as the degree of ordering at bilayer interfaces, thereby presenting a self-consistent picture of the local environment of the tracer molecule.