Vice Chair for Graduate Education
Professor of Chemical and Biomolecular Engineering
The Charles W. Tobias Professor in Electrochemistry
office: 201C Gilman
lab: D52, D72, D80 & D84 Tan
lab phone: (510) 643-5037, 642-8980
Microstructured Polymer Materials, Light and Neutron Scattering
My research is based on soft microstructured materials such as block copolymer melts, polymer microemulsions, and colloidal suspensions. Principles of solid state physics provide a recipe for creating materials with low elastic moduli, G. For crystals, G=1/<x^2>d where <x^2> is the mean square displacement of the atoms, d is the lattice constant. In liquids, the mean square displacement is bounded only by the size of the container. Soft materials are thus characterized by periodic microstructures with relatively large lattice constants (d in the nanometer to micrometer range), fluctuations and disorder (the magnitude of <x^2> can approach d), and liquid crystalline symmetry.
We specialize in studying soft microstructures that self-assemble from the liquid state. The self-assembled nature of the structures that we study has important consequences. These microstructures form spontaneously and do not require machining or microlithography, as is the case with conventional manufacturing. Also, the structure need not be permanently fixed; it can be altered by changing external conditions, like temperature, pressure or stress. Subtle changes in the external conditions could lead to profound changes in the mechanical, optical and electrical properties of the material if they are accompanied by a microstructural transition. These changes could be accomplished repeatedly and reversibly if the structures are at equilibrium. These materials thus have the potential of performing complex functions, if we can understand the physical origins of their complex responses and control them to produce useful results.
My program is concerned with the synthesis of such materials and the quantification of thermodynamic interactions that lead to microstructure formation. We are also developing experimental tools and the theoretical framework necessary to characterize the soft materials. We also use these materials to obtain a fundamental understanding of processes such as nucleation and flow alignment
Professor; Faculty Associate Scientist, LBNL; Ph.D. Rensselaer Polytechnic Institute (1988); National Science Foundation Young Investigator Award (1994); Sigma Xi Distinguished Faculty Research Award, Polytechnic University (1995); 3M Non-Tenured Faculty Award, (1996); Engineer of the Year, American Institute of Engineers of Indian Origin (1997); John H. Dillon Medal, American Physical Society Award for Polymer Physics (1997); Camille Dreyfus Teacher-Scholar Award (1998); Hendrick C. Van Ness Lectureship, Rensselaer Polytechnic Institute (1998); Fellow of the American Physical Society, (2000); Charles M.A. Stine Award, American Institute of Chemical Engineers Award for Materials Engineering and Science (2005).