Surfactant Assemblies on Selected Nanostructured Surfaces: Evidence, Driving Forces, and Applications

Abstract

Surfactant adsorption at solid-liquid interfaces is critical for a number of applications of vast industrial interest and can also be used to seed surface-modification processes. Many of the surfaces of interest are nanostructured, as they might present surface roughness at the molecular scale, chemical heterogeneity, as well as a combination of both surface roughness and chemical heterogeneity. These effects provide lateral confinement on the surfactant aggregates. It is of interest to quantify how much surfactant adsorbs on such nanostructured surfaces and how the surfactant aggregates vary as the degree of lateral confinement changes. This review focuses on experimental evidence on selected substrates, including gold- and carbon-based substrates, suggesting that lateral confinement can have pronounced effects both on the amount adsorbed and on the morphology of the aggregates as well as on a systematic study, via diverse simulation approaches, on the effect of lateral confinement on the structure of the surfactant aggregates. Atomistic and coarse-grained simulations conducted for surfactants on graphene sheets and carbon nanotubes are reviewed, as well as coarse-grained simulations for surfactant adsorption on nanostructured surfaces. Finally, we suggest a few possible extensions of these studies that could positively impact a few practical applications. In particular, the simultaneous effect of lateral confinement and of the coadsorption of molecular compounds within the surface aggregates is expected to yield interesting fundamental results with long-lasting consequences in applications ranging from drug delivery to the design of advanced materials.

DPD Parameters Estimation for Simultaneously Simulating Water–Oil Interfaces and Aqueous Nonionic Surfactants

“…Building on results for the compressibility of water, Groot and Warren 9 related the self-repulsion parameter to the density within the simulation box and to the degree of coarse graining, as shown in Eq. (1): 9,13,14 ii = k B T κ −1 N m − 1 2αρ DPD (1) In this equation ii is the repulsion parameter between same beads, k B is the Boltzmann constant, T is the temperature of the system, κ −1 is the compressibility of water (equals to 15.9836 at 300 K), N m is the degree of coarse-graining, ρ DPD is the density inside the simulation box, and the coefficient α is estimated to be equal to 0.101 ± 0.001.…”

Anionic surfactant induced desorption of a cationic surfactant from mica

“…There is evidence that the 'frontal confinement' caused by the second surface can perturb the system and result in non-equilibrium structures being measured (Speranza et al, 2013;Striolo and Grady, 2017).…”

Novel Amphiphiles and Their Applications for Different Purposes with Special Emphasis on Polymeric Surfactants

“…In this connection we would like to mention here that Gemini surfactants are also extensively used in CEOR like polymeric surfactants. The unique and beneficial properties in the previous section and those properties includes the property of reducing interfacial tension and increasing viscosity of solution, which cause utilisation of Gemini surfactant in CEOR successfully …”