Iron oxide magnetic nanoparticles used as probing agents to study the nanostructure of mixed self-assembled monolayers.

Self-assembled monolayers (SAMs) of organic molecules are of exceptional technological importance since they represent a convenient, flexible, and simple system for tuning the chemical and physical properties of surfaces. The fine control of surface properties is directly dependent on the structure of mixed SAMs which is difficult to characterize at the nanoscale with usual techniques such as scanning probe microscopies. In this study, we report on a general method to investigate at the nanoscale the structure of molecular patterns which consist in SAMs of two components.

Tunable magnetic properties of nanoparticle two-dimensional assemblies addressed by mixed self-assembled monolayers.

Assemblies of magnetic nanoparticles (NPs) are intensively studied due to their high potential applications in spintronic, magnetic and magneto-electronic. The fine control over NP density, interdistance, and spatial arrangement onto substrates is of key importance to govern the magnetic properties through dipolar interactions. In this study, magnetic iron oxide NPs have been assembled on surfaces patterned with self-assembled monolayers (SAMs) of mixed organic molecules.

Monte Carlo simulations of surfactant aggregation and adsorption on soft hydrophobic particles.

Monte Carlo simulations with an explicit description of counterions are performed to investigate the adsorption of ionic surfactants at the interface between water and soft hydrophobic and penetrable particles. The surfactant molecules are represented at a coarse-grained level, their hydrophobic tails interact with each other through a Lennard-Jones potential, whereas their hydrophilic head and their counterions interact through a Coulombic potential. Two colloidal hydrophobic particles interact with the surfactant hydrophobic chains through a modified Lennard-Jones potential.

Surfactant distribution in waterborne acrylic films. 1. Bulk investigation.

The distribution of an anionic surfactant, sodium dodecyl sulfate (SDS), in waterborne acrylic films was investigated, focusing on the effects of particle composition and size, and pH of the latex. The observed surfactant distributions could be classified in two categories: homogeneous and heterogeneous, the latter showing SDS aggregates. The shape of the profiles was related to the stability of the latex during drying, at short interparticular distances.

Occurrence, shape, and dimensions of large surface hemimicelles made of semifluorinated alkanes. Elongated versus circular Hemimicelles. Pit- and tip-centered hemimicelles.

The formation of large (approximately 20-35 nm) surface hemimicelles in monolayers of semifluorinated alkanes, C(n)F(2)(n)(+1)C(m)H(2)(m)(+1) (FnHm), observed after transfer onto silicon wafers, is a general phenomenon. F6H16 and F8H14 exclusively form highly monodisperse circular hemimicelles, organized in a hexagonal array. The other FnHm investigated form both circular and elongated hemimicelles.

Cosurfactant effect of a semifluorinated alkane at a fluorocarbon/water interface: impact on the stabilization of fluorocarbon-in-water emulsions.

Previous work has demonstrated that semifluorinated alkanes CnF2n+1CmH2m+1 (FnHm diblocks), when used in conjunction with phospholipids, strongly stabilize fluorocarbon (FC)-in-water emulsions destined to be used as oxygen carriers. Although the presence of FnHm diblocks in the emulsion's interfacial phospholipid film was suggested to account for the observed stabilization, no direct proof of the diblock's location has been provided so far. We now report definite experimental evidence of the diblock's presence at the interfacial film, both on a macroscopic level by investigating the FC/water interface using the pendant drop method and directly on emulsions by monitoring their stability for various phospholipid chain lengths.