Research Initiative


Site Design:
 Jeff Frey

Copyright © 2002

People - Jan Boshoff

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.

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

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

My Code Resources
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".

Get the code!