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William B. Russel

William Russel

Dean of the Graduate School
Arthur W. Marks '19 Professor of Chemical and Biological Engineering
Ph.D. 1973, Stanford University

Research interests include (a) patterning thin polymer films spin cast on silicon wafers via instabilities driven by electric fields between the wafers or tensile stresses as the wafers are separated and (b) cracking or collapse phenomena in colloidal dispersions. In both cases, well-known physical forces acting at submicron scales produce unexpected phenomena.

For example, positioning a mask 100 nm above a thin polymer film on a silicon wafer and heating above the glass transition yields remarkable periodic patterns. Alternatively, prying apart, at room temperature, two silicon wafers bonded with a polymer layer leaves parallel lines of polymer that extend for millimeters. For each the spacing can be varied from millimeters to submicron.

Drying colloidal dispersions to produce impermeable or porous films also can be disrupted by cracking, which is driven by tremendous capillary pressures that cause elastic deformation of the particles. In the absence of drying or other disturbances, colloidal gels stored in a quiescent state may suddenly collapse into a dense sediment, due to a combination of thermodynamic and mechanical forces.