Nano
Porous
Carbon
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UD
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| Research Initiative |
Webmaster:
email
Site Design:
Jeff Frey
Copyright © 2002
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Research Interests
Molecular transport through nanostructured materials is of
concern in the seperations industry. A lack of understanding
of the fundamental molecular mechanisms controlling transport
of penetrants in nanostructured materials has to a large
extend prevented the effective engineering of novel barrier
materials. This work seeks to address this need by direct
molecular modeling.
We use molecular dynamics simulations to study the
diffusion of small gas penetrants in amorphous, glassy
polymers. In the first part of our work, we looked at
diffusion of a tracer penetrant in a rigid model of amorphous,
glassy polypropylene. Main conclusions about the molecular
mechanisms of diffusion are summarized in the abstract of our
paper, submitted for publication to Macromolecules (see link
below).
Extending our work we are currently studying small gas
penetrant diffusion in polymers adsorbed in mesoporous
materials, such as SBA-15, an ordered mesoporous silica
structure with cylindrical pores on the order of 60 A in
diameter.
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Resources
Publications
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Boshoff, J.H.D.; Lobo, R.F; Wagner, N.J.
The Influence of Polymer Motion, Topology and
Simulation Size on Penetrant Diffusion in Amorphous,
Glassy Polymers: diffusion of He in Polypropylene.
Macromolecules 2001 34, 6107-6116
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Presentations
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Boshoff, J.H.D; Lobo R.F.; Wagner, N.J.
Diffusion of He in Frozen Polypropylene
Structures: Polymer Density & Simulation Size
Effects .
Poster at AIChE Annual Meeting 2000, Los Angeles,
CA
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My Code Resources
UDskip
UDskip is a Fortran 90 program to calculate
theoretical Powder X-Ray diffraction patterns of
ultrasmall zeolite crystals. The program uses an
algorithm proposed by Schlenker & Peterson in
Journal of Applied Crystallography
(1996 29,178-185).
UDskip allows one to calculate accurate
powder X-Ray diffraction patters for crystals as
small as one unit cell. Peak broadening due to
the small crystal size is directly taken into
account. The two-dimensional integral over the
scattering cross-section is performed using
Romberg-integration, with trade-off between
efficiency and numerical accuracy specified by the
user.
Although the program was developed for zeolites,
the program will calculate Powder X-Ray diffraction
patterns for any crystal for which the scattering
cross-sections of the atoms are known.
To compile UDskip you will need the freely
available graphics library
PGPLOT.
The latest version of UDskip is 1.0.
For usage instructions, start the
program with no command line parameters. See also
the "sample.input" for a sample input file and the
eps image "sample.results.eps" for the pattern you
should expect from "sample.input".
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