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NSF Career Award Projects Underway
 Jason
Butler's Career Award project focuses on the Dynamics, Rheology, and
Microrheology of Rigid Polymers and Brownian Fibers. Rigid polymers are
widely used as high-performance plastics. Examples of small, Brownian rods can
be found in the form of macromolecules of biological origin and in exciting
nanotechnology applications in the form of nanotubes and nanorods. Processing of
these materials generally takes place with the rods suspended in solution, yet
the dynamics and rheology, or fluid properties, of suspensions of rigid rods are
only understood at a qualitative level. These theories capture the essence of
some observations, but improving products and the efficiency of production for
these materials partly relies on the ability to accurately forecast the behavior
of the suspensions under a wide range of conditions.
To eliminate the disparity between quantitative predictions and measurements,
this project will study the dynamics of these complex fluids using advanced
simulation methods and experimental techniques such as rheology, microrheology,
and light scattering measurements. The expected improvements in methods and
theories used for the evaluation of complex fluids composed of rigid polymers
and Brownian fibers will impact existing and emerging technologies in polymer
science, nanotechnology, and biotechnology.
 Jason
Weaver's Career Award project focuses on the Growth Properties and
Reactivity of Oxygen Phases on Noble Metal Catalysts. Oxidation catalysis by
noble metals is central to pollution control in vehicles, through the catalytic
converter process, and is widely used to transform hydrocarbons into useful
fuels and chemicals. However, the oxygen phases at work on these metals, usually
platinum, palladium, or rhodium, are not well understood at the atomic level.
The objective of the research is to provide a better understanding of these
oxygen phases. Model catalysts will be prepared in ultrahigh vacuum conditions
by growing thin oxide films and then vapor depositing the catalytic metals onto
the films. A low energy atomic oxygen beam will be used to enhance the rate of
oxygen chemisorption on the metals so that the oxygen phases important at
commercially relevant pressures can be prepared and investigated. The research
will significantly advance the understanding of how specific catalyst properties
and oxidizing conditions govern the growth and properties of the surface oxygen
phases that are important to real-world catalysis.
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