1. 07/10/06 Group Meeting1 Patterning of Small Particles & Surface Tension vs. Temperature Lu Zou Group meeting Jul. 10, ’06 Ref: Nguyen, V.X.; Stebe, K. J.; PRL, Vol. 88, 16, 164501, 2002

2. 07/10/06 Group Meeting2 Patterning of Nanoparticles A drop containing finely divided particles Evaporation Particles are deposited in macroscopic patterns Interactions among the particles can be exploited to create local order

3. 07/10/06 Group Meeting3 “ Coffee Ring ” & “ Benard Cells ” R. D. Deegan and others 1997. "Capillary flow as the cause of ring stains from dried liquid drops", Nature, volume 389, pp827-829 Nature M. Maillard, L. Motte, M.-P. Pileni ; Rings and Hexagons Made of Nanocrystals, Adv. Mater. 2001, 13, 200-204 (or say, periodic flow patterns, Hexagon patterns)

4. 07/10/06 Group Meeting4 Why a drying drop forms a “ Coffee Ring ” ? Ref: http://mrsec.uchicago.edu/ Nuggets/Coffee/mrsec.uchicago.edu/ Nuggets/Coffee/

5. 07/10/06 Group Meeting5 Benard Convection physics.ucsd.edu/was-daedalus/ convection/rb.html

6. 07/10/06 Group Meeting6 A Droplet with Surfactant HCl + 0.01% microspheres (D = 0.8um) Pentadecanoic Acid (PDA) Dyed by NBD-HDA Modified SiO 2 Substrate Contact angle for water is 50 o +/- 3 o

7. 07/10/06 Group Meeting7 Isotherm of PDA w/ NBD-HDA

8. 07/10/06 Group Meeting8 For the LC-LE State

9. 07/10/06 Group Meeting9 For the LE State When the interface is in LC- LE coexistence, the Benard convection is present, even though the concentration of the surfactant is significant.

10. 07/10/06 Group Meeting10 2 Possible Explanation In the LE-LC coexistence regime, compositional Marangoni stresses are weak. In the LE-LC coexistence regime, temperature-driven Marangoni stresses are strong.