Center Of Alkyl Chain Research Articles

A mechanism study of sodium dodecylbenzene sulfonate on oil recovery: effect of branched chain structure

The effects of the branched structures of SDBS molecules on oil recovery are investigated by molecular dynamics method. The relative density of oil molecules shows that SDBS molecule with benzene ring located near the center of alkyl chain has the best effect on oil displacement. Dynamic trajectories show that the water and SDBS molecules gradually occupy the calcite surface and replace the oil droplets. In this process, more water molecules gather nearby the polar groups of SDBS, indicating that the polar group has a significant effect on the water infiltration and the formation of water channels. Contact angle between SDBS molecule and calcite surface indicates that compared to straight chains, the branched structure tends to spread on the calcite interface. Moreover, adsorption energies of the simulation systems further prove that as the aromatic ring is closer to the middle of the alkyl chain, the oil displacement effect is better.

Molecular Self‐Aggregation of Tetradecylbenzene Sodium Sulfonate Isomers

AbstractThis paper deals with the effect of the surfactant isomeric structure on self‐aggregation in aqueous solution. The relationship between the molecular structure of a series of tetradecylbenzene sulfonate isomers (with the benzene ring located at different positions along the alkyl chain) and surface tension was made clear. It is found that the critical micelle concentration increases and the surface tension at critical micellar concentration decreases as the benzene group moves toward the center of the alkyl chain. The structure of micelles was studied by 1H‐NMR relaxation, which indicates that the density of methylene protons in the surface layer of the micellar core decreases as the branching of the hydrophobic group increases. The spontaneous vesicle formation in aqueous solution was investigated by transmission electron microscopy. The results reveal that, as the benzene group moves toward the center of alkyl chain, the assembly structure changes from micelle to vesicle, then to lamellar bilayers, while the critical packing parameter increases.