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.


picture of rods
Diffusing rods

We look at the Brownian motion of rods tumbling and drifting in 3D. What does their motion tell us about the viscoelastic properties of their medium?
experimental picture
Confinement and the glass transition

The glass transition is modified in confined spaces, but it's unclear why. We're studying colloidal particles confined between two parallel walls; we find their motion slows down.

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.
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?
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?
PAST PROJECTS
packed spheres Random close packing in confinement: How tightly can you pack a mixture of small and large spheres into a container? And how does the answer change when the container is not much larger than the spheres themselves?
5 tetrahedra 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.
flowing
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.

FUNDING:

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