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Abstract:

This talk will describe mechanistic investigations and applications of space-charge electrets fabricated by contact electrification, the mechanisms of which remain a subject of active controversy at the atomic/molecular level. The polarity of charging during contact electrification of ionic electrets (materials with surface-bound ionic functional groups and oppositely charged, mobile counterions) is consistent with an ion-transfer mechanism for contact electrification. Dielectric breakdown of the surrounding gas limits the maximal density of charge that the electrets can sustain. Oppositely-charged electrets can self-assemble in two and three dimensions, and are useful for studying simplified physical models of complicated processes such as crystallization and the folding of beads on a string. Surfaces fabricated from combinations of oppositely charged ionic electrets can resist contact electrification and prevent electrical discharges. These examples demonstrate that a more developed understanding of electrets in general, and of the mechanisms of contact electrification in particular, can lead to new applications for space-charge electrets.

Bio: George M. Whitesides was born August 3, 1939 in Louisville, KY. He received an A.B. degree from Harvard University in 1960 and a Ph.D. from the California Institute of Technology (with J.D. Roberts) in 1964. He was a member of the faculty of the Massachusetts Institute of Technology from 1963 to 1982. He joined the Department of Chemistry of Harvard University in 1982, and was Department Chairman 1986-89, and Mallinckrodt Professor of Chemistry from 1982-2004. He is now the Woodford L. and Ann A. Flowers University Professor. He is the recipient of numerous honors and awards, including election to the American Academy of Arts and Sciences, National Academy of Sciences, and the National Academy of Engineering as well as the American Chemical Society (ACS) Award in Pure Chemistry, National Medal of Science, and the Von Hippel Award (MRS). Present research interests include physical and organic chemistry, materials science, biophysics, complexity, surface science, microfluidics, self-assembly, micro- and nanotechnology, science for developing economies, origin of life, and cell-surface biochemistry.