Mechanistic study on the effect of benzenesulfonate position on the stability of sodium dodecylbenzene sulfonate-emulsified asphalt

The stability of emulsified asphalt is crucial for engineering applications, where the influence of emulsifiers on stability cannot be overlooked. However, most studies have focused on macroscopic approaches, with few investigating the mechanisms by which emulsifier isomers affect stability at the microscopic level. This study employs molecular dynamics simulations to elucidate further the mechanism by which emulsifier isomers influence the stability of emulsified asphalt on a microscopic scale. Specifically, the research examines the effects of varying sodium dodecylbenzene sulfonate (SDBS) concentration and the position of the benzenesulfonate along the alkyl chain of the SDBS molecule. The focus is on the configurations 4-1ΦC12S, 4-3ΦC12S, and 4-5ΦC12S. The analysis includes diffusion coefficients, interfacial formation energies, relative concentration distributions, and radial distribution functions. The simulation results reveal that 15 % of the 4-1ΦC12S emulsifier exhibits excellent migration ability, reducing interfacial tension and forming a stable interfacial film, thereby enhancing the stability of emulsified asphalt. In contrast, the “double-chain” structure of the 4-3ΦC12S and 4-5ΦC12S configurations causes spatial hindrance, restricting their activity and resulting in weak binding to water molecules. This weak adsorption at the oil–water interface leads to a less compact arrangement, thereby reducing the stability of the emulsified asphalt system. Overall, this microscopic study, utilizing molecular dynamics simulations, offers valuable insights for designing emulsifier molecular structures and enhancing the stability of emulsified asphalt. Moreover, the method can be applied to other emulsified asphalt systems, demonstrating significant potential for broader applications.