Effect of an excess of surfactant on thermophoresis, mass diffusion and viscosity in an oily surfactant-stabilized ferrofluid.

The effect of an excess of surfactant on the thermophoresis of a sterically stabilized ferrofluid is investigated experimentally by forced Rayleigh scattering (FRS). The experiments are performed with a stable magnetic fluid sample to which controlled amounts of surfactant are added. A decrease in the thermally induced transport of magnetic nanoparticles is observed while increasing the temperature T.

Manifestation of dipole-induced disorder in self-assembly of ferroelectric and ferromagnetic nanocubes.

The colloidal processing of nearly monodisperse and highly crystalline single-domain ferroelectric or ferromagnetic nanocubes is a promising route to produce superlattice structures for integration into next-generation devices, whereas controlling the local behaviour of nanocrystals is imperative for fabricating highly-ordered assemblies. The current picture of nanoscale polarization in individual nanocrystals suggests a potential presence of a significant dipolar interaction, but its role in the condensation of nanocubes is unknown. We simulate the self-assembly of colloidal dipolar nanocubes under osmotic compression and perform the microstructural characterization of their densified ensembles.

Self-assembly and rheology of dipolar colloids in simple shear studied using multi-particle collision dynamics.

Magnetic nanoparticles in a colloidal solution self-assemble in various aligned structures, which has a profound influence on the flow behavior. However, the precise role of the microstructure in the development of the rheological response has not been reliably quantified. We investigate the self-assembly of dipolar colloids in simple shear using hybrid molecular dynamics and multi-particle collision dynamics simulations with explicit coarse-grained hydrodynamics, conduct simulated rheometric studies and apply micromechanical models to produce master curves, showing evidence of the universality of the structural behavior governed by the competition between the bonding (dipolar) and erosive (thermal and/or hydrodynamic) stresses.

Numerical investigation of thermo-magneto-solutal flow of ferrocolloid through ordered and disordered permeable membranes.

We explore the mechanism of ferroparticle transfer in porous structures in the conditions of simultaneous action of the thermal gradient and the magnetic field. We show that when a ferrocolloid saturated porous matrix is placed in a homogeneous magnetic field the grains of the porous frame notably distort the uniformity of the internal field by creating sharp gradients in the vicinity of the interface. On the other hand, the application of the temperature gradient creates an imbalance of the ferroparticle concentration in the bulk of the porous structure due to colloidal thermophoresis.

Relaxation mechanisms of photoinduced periodic microstructures in ferrofluid layers.

We consider theoretically and numerically a periodic concentration grating induced in a layer of ferrofluid in the presence of the external magnetic field by nonuniform optical heating through photoabsorption. The stationary profiles of the periodic microstructures are governed by the equilibrium of the diffusive, thermodiffusive, and magnetic fluxes. The anisotropy of the diffusion coefficient and the magnetically driven microconvection contribute to the relaxation of these structures.

Magnetically driven microconvective instability of optically induced concentration grating in ferrofluids.

In this paper, we consider a concentration grating of magnetic nanoparticles optically induced by thermodiffusion in a layer of ferrofluid in the presence of the external homogeneous magnetic field. The applied field is directed along the concentration gradient and leads to the appearance of the internal nonhomogeneous demagnetizing fields. When the system reaches equilibrium, the optical pumping is switched off, and the grating is allowed to relax.