Molecular dynamics simulations of the quick micelle formation of Azotab in D2O solution: Micellar structure and the swing of two benzene rings

COMP 247

Chih-Ying Lin, chihying@usc.edu1, Katherine Shing, shing@usc.edu2, and C. Ted Lee, tedlee@usc.edu1. (1) Department of Chemical Engineering and Materials Science, University of Southern California, 925 Bloom Walk, HED 216, Los Angeles, CA 90089-1211, (2) Department of Chemical Engineering and Material Science, University of Southern California, 925 Bloom Walk, HED 216, Los Angeles, CA 90089-1211
Azotab, CH3-CH2-(C6H4)-N=N-(C6H4)-O-(CH2)4-N(CH3)3-Br, is a photo-controlled surfactant with both cis and trans structrures. Unlike other surfactants, azotab carries with a big tail, a pair of benzene rings. Starting as random configurations, the molecular dynamics simulations plus DIP3P water model were performed. This study suggested that the swing of the two benzene rings contributes the fast diffusion rate as well as the quick micelle formation of azotab within 20 ns at the concentration near CMC (~10 mM). We measured the swing rate for each benzene ring and the diffusion rate for a single azotab in D2O solution. We also defined the compact degree of micelle and compared the structural analysis between cis and trans azotab-micelles and see if any structural difference for various sizes of micelles. The simulation told us that the mixture of cis and trans azotabs in D2O solution possibly forms a micelle. Our predicted gyration radius distribution corresponds to the experimental data.
 

Poster Session
6:00 PM-8:00 PM, Tuesday, August 18, 2009 Walter E. Washington Convention Center -- Ballroom A, Poster

Division of Computers in Chemistry

The 238th ACS National Meeting, Washington, DC, August 16-20, 2009