A Computational Study of the Molecular Structure and Dynamics of Porous Silica Aerogels |
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Materials:
Ceramics
Composites
Application: Nanotechnology Structural Technique: Computation |
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Silica aerogels are a versatile class of materials with a host of applications ranging from thermal insulation in household refrigerators and solid-state Cherenkov detectors to passive solar energy collection devices and interstellar dust collectors on NASA's Stardust spacecraft . The unique properties of aerogels - an extremely low thermal conductivity, for instance - result from the porosity in their structure, which may be as high as 95%. Aerogels have been shown to behave as random, non-Euclidean fractals - they exhibit self-similarity over at least two orders of magnitude in length. This fractal structure makes the study of the physical properties of aerogels a particularly interesting scientific problem. <br>We are using molecular dynamics (MD) techniques to model the structure and physical properties of silica aerogels by reproducing the widely used sol-gel condensation reaction. An accurate simulation of the sol-gel process allows us to create realistic aerogel structures - we then use geometrical correlations to calculate their fractal dimension. We have shown that the effect of supercritical drying of silica gels on their fractal dimension is negligible (1). We are currently investigating the effect of aqueous solvent on the condensation reaction and the mobility of the silica clusters in the system, as well as on the structure and properties of condensed gels. Finally, we are using energy minimization methods and normal mode analysis to investigate the vibrational modes of the porous gel structures. |
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Materials Science and Engineering, University of Michigan
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- A Computational Study of the Molecular Structure and Dynamics of Porous Silica Aerogels
| P.I.: | John Kieffer |
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