Surface Interaction of Nanoscale Water Film with SDS from Computational Simulation and Film Thermodynamics

Abstract

Foam systems have been attracting extensive attention due to their importance in a variety of applications, e.g., in the cleaning industry, and in bubble flotation. In the context of flotation chemistry, flotation performance is strongly affected by bubble coalescence, which in turn relies significantly on the surface forces upon the liquid film between bubbles. Conventionally, unusual short-range strongly repulsive surface interactions for Newton black films (NBF) between two interfaces with thickness of less than 5 nm were not able to be incorporated into the available classical Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory. The non-DLVO interaction would increase exponentially with the decrease of film thickness, as it plays a crucial role in determining liquid film stability. However, its mechanism and origin are still unclear. In the present work, we investigate the surface interaction of free-standing sodium dodecyl-sulfate (SDS) nanoscale black films in terms of disjoining pressure using the molecular simulation method. The aqueous nanoscale film, consisting of a water coating with SDS surfactants, and with disjoining pressure and film tension of SDS-NBF as a function of film thickness, were quantitatively determined by a post-processing technique derived from film thermodynamics.

Molecular Simulation Study on the Microscopic Structure and Mechanical Property of Defect-Containing sI Methane Hydrate

“…The systems after deletion of various percentages of particles were performed stable relaxation; firstly, the isothermal–isochoric (NVT) ensemble [49] (number of particles (N), volume (V), and temperature (T)) was relaxed for 1,000,000 steps at 200 K at the time step of 0.2 fs ; subsequently, the isothermal–isobaric (NPT) ensemble [50] (number of particles (N), pressure (P), and temperature (T)) was relaxed under 200 K and 10 MPa conditions for 1,000,000, with the time step of 0.2 fs .…”

Molecular dynamic simulation of the molecular characteristic and mechanical property of methane hydrate/ water/ ice mixture

“…1 is the simulation model for 2 × 2 × 10 unit cells of sI methane hydrate deleting the methane molecules at both ends, in which the red particle is O atom of water molecule, the white particle is H atom of water molecule, and the brown particle is methane molecule. In the simulation, LJ hard sphere model is used to describe the interaction between methane molecules, and TIP4P model [29] is adopted to describe the physical and chemical properties of water molecules. The TIP4P model consists of four particle points, and the electrons and protons of the middle oxygen atom are not coincided.…”

Thermodynamic Insights of the Molecular Interactions of Dopamine (Neurotransmitter) with Anionic Surfactant in Non-Aqueous Media

“…Compared to different drug carrier systems, the surfactant micelles physically entrap the drug molecules inside their core with a minor toxicity, longer residence in the system, and better bioavailability and stability of the drug through micelle assimilation [ 22 , 23 ]. However, besides experimental study, molecular simulation has been used to study the surface interaction of nanoscale black films made from free-standing sodium dodecyl-sulfate (SDS) in terms of disjoining pressure [ 24 ]. In addition, the small RGD (1FUV) polypeptide in various environments and the subdomain SD1 of the SARS-CoV-2 spike protein were studied using the ab initio QMRPA method to obtain their respective dielectric spectra, partial charges, and AA bond order [ 25 ].…”