We study the statistical mechanics of "soft condensed matter:" colloids, vesicles, emulsions, nanoparticle suspensions and other squishy things. Our experiments probe the relationships among inter-particle forces, structure, and dynamics of many-bodied systems -- relationships that are central to research in condensed-matter physics.

We use this fundamental understanding to develop materials at the nanometer scale. Self-assembled materials have truly unique mechanical, optical and electronic properties with applications in nanotechnology and biomedical engineering.

Click on images for details. Publications can be downloaded.

We apply optical imaging in 2D and 3D; laser tweezers and micromanipulation; a station for vis-IR optical spectroscopy of microscopic samples; and a lab for synthesis of polymeric, metallic, semiconducting and insulating particles, droplets, and membranes. We use a fast-scanning confocal microscope (> 100 fps) to track motions in 3D. We also share a fast camera facility (up to ~100,000 fps) with Menon, Candela, and Easwar.

Random Solids - gels and droplet piles:
Thermal motions, forces, topology, and elasticity.
(Published in Science, 6/16/06)

Melting & Freezing of Colloidal Crystals:
Dynamics probed with single-particle resolution.
(Published in Science, 11/3/06)

Colloids and Electronics:
Metallic droplets; transistors assembled in solution.

Solid Particles at Liquid Interfaces:
Electrostatic & capillary forces at interfaces;
Nanoparticle membranes formed on droplets;
Self-assembled capsules for delivery (colloidosomes).

Colloids and Optics:
Scattering and diffusion of light in randomly
packed films.

Cylindrical Fluid Structures: hydrodynamic
focusing of viscoelastic fluids.
(Published in Langmuir, 8/2006)

Hydrodynamics of Spherical Viscous Membranes:
flow field around a rod moving on a sphere.

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Former Projects: Entropic forces near rigid
and flexible surfaces:

Doped semiconductor nanoparticles:

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We gratefully acknowledge support from the following organizations: National Science Foundation. National Aeronautics & Space Administration. Research Corporation. Center for UMass/Industry Research on Polymers (CUMIRP) Materials Research Science & Engineering Center on Polymers at UMass. Kraft Foods, Inc. Xerox Corporation (University Affairs Committee).