Location
Cherry Auditorium, Kirk Hall
Start Date
3-10-2022 12:45 PM
Description
Block polymers have captured the interest of scientists and engineers for more than half a century. In general, the phase behavior of A-B diblock copolymers, the simplest category of such self-assembling macromolecules, has been accepted as thoroughly understood. Experiments and theory conducted over the past decade have revealed remarkable phase complexity in the limit of asymmetric compositions, where the A block is considerably shorter than the B block, resulting in the formation of nanoscale micelles. Small-angle x-ray scattering (SAXS) measurements have revealed the formation of various low symmetry Frank-Kasper phases and a dodecagonal quasicrystal, reflecting fascinating analogies with the phase behavior of metal alloys. These findings will be discussed in the context of a competition between the tendency to form spherical particles and the constraints associated with filing space at uniform density.
Speaker Bio
Frank S. Bates is a Regents Professor and a member of the Chemical Engineering and Materials Science department at the University of Minnesota. He received a B.S. in Mathematics from SUNY Albany and M.S. and Sc.D. degrees in Chemical Engineering from MIT. Between 1982 and 1989 Bates was a member of the technical staff at AT&T Bell Laboratories then joined the University of Minnesota where he served as department Head from 1999 to 2014. He was named a Regents Professor in 2007. Bates conducts research on a range of topics related to polymers, including the thermodynamics, dynamics, structure, and properties of block polymers, polymer blends and solutions. He is a member of the US National Academy of Engineering and the National Academy of Sciences, the American Academy of Arts and Sciences, and the National Academy of Inventors.
Sphericity and Symmetry Breaking in Asymmetric Diblock Copolymer Melts
Cherry Auditorium, Kirk Hall
Block polymers have captured the interest of scientists and engineers for more than half a century. In general, the phase behavior of A-B diblock copolymers, the simplest category of such self-assembling macromolecules, has been accepted as thoroughly understood. Experiments and theory conducted over the past decade have revealed remarkable phase complexity in the limit of asymmetric compositions, where the A block is considerably shorter than the B block, resulting in the formation of nanoscale micelles. Small-angle x-ray scattering (SAXS) measurements have revealed the formation of various low symmetry Frank-Kasper phases and a dodecagonal quasicrystal, reflecting fascinating analogies with the phase behavior of metal alloys. These findings will be discussed in the context of a competition between the tendency to form spherical particles and the constraints associated with filing space at uniform density.
Comments
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