A novel erucic acid derived surfactant: Experimental and theoretical study

Abstract

Erucic acid is still a difficulty to utilize efficiently as a byproduct of grease processing. An effective strategy is to develop novel surfactants derived from erucic acid. Adamantyl trimethyl ammonium erucate, (AdEr) is an ionic liquid anionic surfactant derived from erucic acid. In this study, a combination of experimental and theoretical calculations was used to compare its physical characteristics and aggregation behaviors with the previously reported choline erucate (ChEr). The physical chemical properties were evaluated by differential scanning calorimetry (DSC), thermogravimetric analysis, surface tension and dynamic light scattering (DLS). The introduction of adamantane enhanced thermal stability and increased the melting point, while maintaining the excellent water-solubility. In comparison with ChEr, AdEr has a lower critical micelle concentration (CMC) and lager micellar aggregation sizes, exhibiting better micellization ability. Density functional theory (DFT) calculations suggests that AdEr has less intramolecular activity and a more stable molecular structure. Molecular dynamic (MD) simulations verified that AdEr preferred to aggregate to form micelles and had a larger aggregation size than ChEr using parameters such as conformation snapshots, radius of gyration (Rg) and mean square displacement (MSD). According to radial distribution function (RDF) analysis, this is owing to the smaller occupied area due to lower hydration of COO− groups of AdEr, and the difference hydration extent of the cations (Ad+ and Cho+). These findings clearly suggest that AdEr can be used as a potential alternative to conventional surfactant derived from erucic acid for various applications.