Molecular Investigations on the Behaviours of Surface-Active Materials

This thesis applied molecular dynamics techniques, a powerful method based on factual observations at nanoscales, to effectively understand macroscopic and microscopic behaviors of surface-active materials in biphasic systems. First, few works have been focused on revealing the effect of naturally occurring organic materials such as naphthenic acids on the behaviors of polyaromatic compounds (known as asphaltenes that are interfacially active) during oil production. To bridge this gap, a series of MD simulations were performed to investigate the effects of molecular structures. It was revealed that naphthenic acids, depending on the solvent type, can either hinder or enhance nano-aggregation among asphaltene molecules. Furthermore, they can affect the orientations of polyaromatic molecules at the oil/water interface. The second direction of this thesis investigated biphasic systems in daily life, i.e., wastewater containing soap. The results obtained shed light on fundamental understandings and utilizations of surface-active materials during industrial applications and in our daily life.