(78c) Thermodynamic Scaling Laws for Surfactant Interfacial Properties

There are volumes of literature that report thermodynamic interfacial properties of nonionic surfactants. However, there exists no theory that links chemical structure to changes in thermodynamic parameters. While previous studies have attempted to link the size of the hydrophobic tail group to the critical micelle concentration, equilibrium interfacial concentration, and equilibrium rate constant, these trends do not account for the head group. In this work we propose simple thermodynamic scaling arguments for surfactant interfacial properties. Using first principles, we propose a simple correlation of thermodynamic parameters to chemical structure. We demonstrate the efficacy of this technique by correlating known literature data for a wide variety of polyethylene glycol mono alkyl ether surfactants. From this approach, we gain both a master curve for properties of this widely used surfactant family as well as deeper understanding of general surfactant structure-property relationships.