Pickering–Ramsden emulsions and other forms of particle stabilized soft materials have received quite some attention recently because the relative ease formulation possibility to create novel materials. There is, however, a clear need for approaches that are versatile efficient. In present work effect aspect ratio particles on stability both water-in-oil oil-in-water is investigated experimentally. Two types non-spherical used. Hydrophobic prolate ellipsoids with ratios ranging from 1 9...

Colloidal particles confined at liquid interfaces have important applications, for example in the stabilization of emulsions and foams. Also self-assembly offers potential novel applications structured particle films. As colloidal interactions differ from those bulk, microstructures can be achieved an interface which cannot produced bulk. In present work shape, surface charge, wetting properties are varied, resulting a fluid is studied. Model monodisperse micrometer-sized ellipsoidal were...

The deposition of material at the edge evaporating droplets, known as 'coffee ring effect', is caused by a radially outward capillary flow. This phenomenon common to wide array systems including colloidal and bacterial systems. role surfactants in counteracting these coffee depositions related occurrence local vortices Marangoni eddies. Here we show that swirling flows are universal, not only lead uniform colloids but also occur living Experiments on Pseudomonas aeruginosa suggest...

Abstract Confinement of living microorganisms and self-propelled particles by an external trap provides a means analysing the motion behaviour active systems. Developing tweezer with trapping radius large compared swimmers’ size run length has been experimental challenge, as standard optical traps are too weak. Here we report novel use acoustic to confine in two dimensions over distances length. We develop near-harmonic demonstrate crossover from weak confinement, where probability density...

We review the sequences of structural states that can be induced in colloidal suspensions by application flow. Structure formation during flow is strongly affected delicate balance among interparticle forces, Brownian motion and hydrodynamic interactions. The resulting non-equilibrium microstructure turn a principal determinant suspension rheology. Colloidal with near hard-sphere interactions develop an anisotropic, amorphous structure at low dimensionless shear rates. At high rates,...

Rheological measurements are used to compare clay nanocomposites prepared through melt mixing using two different polypropylene matrices. Steady state and transient nonlinear rheological experiments employed separate the contributions of flow induced orientation tactoids particulate network build-up. The conditions under which properties dominated by aggregate subsequently identified. Under these conditions, low frequency linear viscoelastic behavior is analyzed scaling concepts for fractal...

The forces between colloidal particles at a decane-water interface, in the presence of low concentrations monovalent salt (NaCl) and surfactant sodium dodecyl sulfate (SDS) aqueous subphase, have been studied using laser tweezers. In absence electrolyte surfactant, particle interactions exhibit long-range repulsion, yet variation interaction for different pairs is found to be considerable. Averaging over several was hence necessary obtain reliable assessment effects surfactant. It has...

The controlled generation of 2D aggregate networks is studied experimentally using micrometer-sized polystyrene latex particles attached to the oil-water interface. Starting from an initially crystalline monolayer, appropriate combinations carefully added electrolyte and surfactant enable control over both fractal dimension kinetics aggregation. Remarkably, colloidal crystals formed upon first spreading remain stable, even for days, when substantial amounts are aqueous phase. Pressure-area...

The behavior of monolayers monodisperse prolate ellipsoidal latex particles with the same surface chemistry but varying aspect ratio has been studied experimentally. Particle at an air−water interface were subjected to compression in a Langmuir trough. When pressure measurements and microscopy observations combined, possible structural transitions evaluated. Ellipsoids sufficiently large display less abrupt increase isotherms than spherical particles. Microscopic reveal that sequence is...

The magnetic interfacial needle stress rheometer is a device capable of sensitive rheological measurements. Yet even for this device, when measuring interfaces with low elastic and viscous moduli, the system response instrument contributes significantly to measured response. To determine operation limits rod rheometer, we analyze relative errors that are introduced by linearly subtracting contribution from An analysis fluid mechanics demonstrates intimate coupling between flow field at...

Blending of two or more immiscible polymers is an attractive route to generate new materials. However, during processing in the liquid state, flow-induced microstructure changes continuously due a complex interplay between break-up and coalescence, typically resulting coarse morphology with poor properties. Hence, need stabilize fine obvious block copolymers are used as compatibilizers. The use nanoparticles has been suggested be alternative 'compatibilize' polymer pairs. In present work,...

The electrostatic interaction of charged spherical colloids trapped at an interface between a nonpolar medium and water is analyzed. Complementary experiments provide consistent values for the dipole-dipole potential over wide range interparticle distances. After accounting contribution from compact inner double layer arising finite size counterions, we demonstrate quantitative agreement nonlinear Poisson-Boltzmann theory. We find that dominates in far field particles pinned interface. This...

Abstract Rheological effects may complicate the dispensing of complex fluids, when compared to their Newtonian counterparts. In this work, fluids with tailored rheological properties have been studied using high‐speed video‐microscopy. The level viscosity, degree shear thinning, and elasticity varied independently. At low‐flow rates, droplets are formed that pinch off. drop volumes, breakup mechanisms, times identified. higher‐flow a continuous jet is observed, transition depending on...

Abstract Current theoretical attempts to understand the reversible formation of stable microtubules and virus shells are generally based on shape-specific building blocks or monomers, where local curvature resulting structure is explicitly built-in via monomer geometry. Here we demonstrate that even simple ellipsoidal colloids can reversibly self-assemble into regular tubular structures when subjected an alternating electric field. Supported by model calculations, discuss combined effects...

In the present work, we investigate mechanisms affecting stability of surfactant-laden thin films during spreading, using drainage flows from a hemispherical dome. Three commercial lung surfactant replacements Survanta, Curosurf and Infasurf, along with phospholipid dipalmitoylphosphatidylcholine (DPPC), are used.

Thin liquid films arise in many technological applications and biological phenomena. They also present a fascinating object of study, because rich interplay between capillarity, hydrodynamics, interfacial transport phenomena rheology, as well the effects interaction forces when thin down to molecular thicknesses. Recent advances experimental techniques have given further insights variety physical phenomena, which can occur. These are briefly reviewed. How these be utilised is illustrated by...