Fourier transform infrared spectroscopy in surfactant science: A personal view

Abstract

AbstractThe overall goal of this review paper on Fourier transform infrared spectroscopy (FT‐IR) is to provide non‐specialists and spectroscopists alike a motivational introduction to how this technique may be used to obtain unique structural information on a wide range of surfactant‐based systems. Two main topics are addressed—The structures of surfactant aggregates in solution and the interactions of surfactants in solution with solid surfaces. Infrared spectra can yield insights into the interactions of surfactants in mixed micelles as well as in microemulsions. The structures of adsorbed surfactant layers and their kinetics of formation may be elucidated from FT‐IR spectra obtained using attenuated total reflectance sampling techniques. Insights into the detergency process of solid oily soils may also be obtained from the spectra of phases formed at the soil‐surfactant solution interface. Future work in applying FT‐IR to the development of the hydrophilic–lipophilic difference + net average curvature (HLD‐NAC) framework is proposed. Spectral interpretation principles examined in many examples, particularly regarding surfactant hydration and the loci of oil solubilization, could be used in the further development of HLD‐NAC through application to some microemulsion systems that have recently been reported.