CiteULike: dchen confinment

Structure and dynamics of confined foams: a review of recent progress.

D Weaire — 2008-07-24T15:08:23-00:00

Advances in colloid and interface science, Vol. 137, No. 1. (28 February 2008), pp. 20-26.

Basic research on confined foams now points to an interesting application, a kind of microfluidics which deals with the manipulation of closely packed droplets or bubbles flowing in channels. In such systems, the minimisation of interfacial energy leads to self-organised ordering which is tightly coupled to the channel geometry, hence providing efficient means of performing controlled topological operations on droplet and bubbles structures. We have called this discrete microfluidics, and have begun to explore its possibilities and principles. Apart from the fact that such systems provide powerful tools to study the flow of foams and emulsions on the scale of a few bubbles or droplets, they also carry the promise of versatile applications for Lab-on-a-Chip technologies. In these, discrete gas or liquid samples can be generated, processed, stored and analysed within a single handheld chip. Previous work on foams and emulsions in confined geometries provides a basis for this, and is being extended progressively by new experiments and appropriate dynamic models, such as the 2d Viscous Froth Model. The result should be a practical "design kit" for more complex networks to efficiently process discrete gas and fluid samples.

Particle dynamics within a wetting layer in a colloid-polymer mixture

P Voudouris — 2008-06-08T20:04:09-00:00

Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 77, No. 5. (2008)

The near-wall dynamics at the top and bottom phases of a phase-separated colloid-polymer mixture were measured by evanescent-wave dynamic light scattering. The short-time dynamics near the wall were found to be liquidlike in both phases, confirming the presence of a liquid wetting layer. The short-time diffusion within the wetting layer was slower than in the bulk liquid phase. Similarly, the near-wall dynamics in both phases of the colloid-polymer mixture were also slower compared to the near-wall colloidal dynamics in a pure concentrated suspension at the same volume fraction. These effects highlight the role of interparticle attractions and specific wall-induced hydrodynamic interactions in slowing down the colloidal motion in confinement.

Exotic crystal superstructures of colloidal crystals in confinement

Ana Fontecha — 2008-06-08T18:22:55-00:00

Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 77, No. 6. (2008)

Colloidal model systems have been used for over three decades for investigating liquids, crystals, and glasses. Colloidal crystal superstructures have been observed in binary systems of repulsive spheres as well as oppositely charged sphere systems showing structures well known from atomic solids. In this work we study the structural transition of colloidal crystals under confinement. In addition to the known sequence of crystalline structures, crystal superstructures with dodecagonal and hexagonal symmetry are observed in one component systems. These structures have no atomic counterpart.

The Mysterious Glass Transition

James Langer — 2008-05-03T19:19:58-00:00

Physics Today, Vol. 60, No. 2. (2007), pp. 8-9.