Weeks Soft Matter Laboratory

Prof. Eric R. Weeks, Physics Department, Emory University

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Suspensions of densely packed colloidal particles are a simple model system which exhibits a glass transition, as the concentration of the particles is increased. We use confocal microscopy to look at the particles and determine how their motion changes as the glass transition occurs. We study these materials in situations including flow through tubes and being poked with tiny magnetic beads. These experiments give us insights into the glass transition in a fashion impossible for regular glasses.

We also study the properties of other complex materials, including foams and sand. See below for information about our various projects.

clogging picture
Clogging of soft particles

We study the clogging of soft particles such as hydrogels and oil droplets, finding the probability that they clog when they drain out a funnel.
plastic rods in a
transparent container
Random close packing

How do rods pack randomly in a container? What about mixtures of different sized spheres? We've done experiments and simulations to answer these sorts of questions.

experimental picture
Confinement and the glass transition

The glass transition is modified in confined spaces, but it's unclear why. We study colloidal particles confined between two parallel walls or in droplets or other small spaces; we find their motion slows down in these small systems.

landscape picture
Free energy landscapes

We've studied three simple model systems where we can directly compute and visualize free energy landscapes.
emulsion picture
Emulsion glasses

We visualize how droplets deform in a concentrated emulsion. In some circumstances emulsions can act like a glass, and studying the deformed droplet shapes should help us understand the emulsion glass transition.
stirred picture
Poking colloids with magnets

We put small magnetic beads into colloidal glasses and pull on them with really strong neodymium magnets. How does this disturb the particles?
soap film
Microrheology of interfaces Is the interface between oil and water a truly two dimensional object, or are three dimensional effects important for microscopic motion along the interface? What about soap films?
aging curves picture Aging of colloidal glasses: Glasses are nonequilibrium systems, and as such, their properties are constantly evolving. We look for the microscopic details of this evolution.
experiment picture Microscopic behavior of flowing colloids: We studied the behavior of colloids as they flow through tiny tubes. As they flow faster, the apparent viscosity decreases. What is the microscopic behavior responsible for this?
picture of gel Structure of colloidal gels: We studied the structure and dynamics of colloidal gels. How does the gel change when we vary the stickiness of the particles?
foam picture Draining water from foam: As water flows between bubbles in a foam, does it flow like regular flow through a pipe? We found that it depends on the type of soap used to make the foam. Work done in collaboration with Stephan Koehler.

  • Diffusing rods: We looked at the Brownian motion of rods tumbling and drifting in 3D.
  • Tetrahedral structure in aging colloids: As colloidal glasses age, does their structure change? We find not, but that the local structure is correlated with the dynamics of the particles.
  • NASA PCS-3 -- study of aging

    Any opinions, findings, and conclusions or recommendations expressed in this website are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Nor anybody else's views, for that matter, just us. Contact Eric Weeks at erweeks(at)emory.edu.