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Sublimation in Colloidal Crystals

Sublimation in Colloidal Crystals. Kevin Schoelz Mentor: Amit Chakrabarti Thanks to Siddique Khan. Asakura-Oosawa Potential. Entropic “Force” Bringing the colloidal particles together reduces the depletion zone of the polymers. Depletion Zone. Asakura-Oosawa Potential. Energy.

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Sublimation in Colloidal Crystals

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  1. Sublimation in Colloidal Crystals Kevin Schoelz Mentor: Amit Chakrabarti Thanks to Siddique Khan

  2. Asakura-Oosawa Potential • Entropic “Force” • Bringing the colloidal particles together reduces the depletion zone of the polymers Depletion Zone

  3. Asakura-Oosawa Potential Energy Interaction range

  4. Phase Diagram

  5. Sublimation in 2D • 2006 paper by Savage et. al. • “Transient Liquid” • Measures Order • y6=ei6ø

  6. Sublimation in 3D t=50 t=0 t=5,000 t=10,000

  7. Geometry of a melting sphere • Assume crystal is spherical • Assume even particle loss • Then, Nm~3R0 ∆R~ ∆V R0 ∆R

  8. Linear Regime Geometry of a melting sphere

  9. Sublimation • Crystals were formed at 4kT • Crystals melted at at 2kT, 2.5kT, 3kT and 3.5kT • At 2kT, sublimation was too quick: exponential behavior? • Other energy levels exhibited scaling

  10. Monomers

  11. Kinetics of 3D Sublimation • Looked at several possible sublimation mechanisms • Particles come from • Surface? • Entire volume? • Edges and boundaries?

  12. Kinetics of 3D Sublimation • Adding an interaction term to the equation provides promising results

  13. Real World Applications • The AO potential is useful in studies of insulin • Insulin in gel form • Breaks up into droplets

  14. Real World Applications

  15. Sources • Imaging the Sublimation Dynamics of Colloidal Crystallites. J. R. Savage, D. W. Blair, A. J. Levine, R. A. Guyer, A. D. Dinsmore Science 3 November 2006:Vol. 314. no. 5800 • Insulin Particle Formation in Supersaturated Aqueous Solutions of Poly(Ethylene Glycol). Bromberg L., Rashba-Step J., Scott T. Biophysical Journal Vol 89, Nov 2005, 3424-3433 • Programs provided by Amit Chakrabarti and Siddique Khan • Funded by National Science Foundation Grant 0855159

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