Exploratory study of dielectric properties of insoluble monolayers: Molecular models

摘要

Studies of insoluble monolayers built of phospholipids, various long-chained fatty acids, and their glycerin esters are the major source of our current knowledge about the relationship between monolayer composition and its physicochemical properties. Such are the surface pressure, dipole moment, dielectric permittivity, polarizability, refractivity, and other electrical and optical features governed by the surfactant structural specificity and solvent organization at the microscopic level. Therefore, model monolayers at the air/water interface of two surfactants that are distinctly different in composition and isotherm profile are investigated by means of a Monte Carlo/molecular mechanics computational procedure. The combination of experimental and theoretical results permits estimation of empirically unattainable quantities and a detailed insight in the interfacial molecular organization at different surface concentrations as well as an evaluation of the surfactant/water contributions to the overall monolayer characteristics. The employed theoretical approach provides a comprehensive description of phenomena at the molecular level where the traditional phenomenological investigations are ineffective. (c) 2006 Wiley Periodicals, Inc.