Coarse-grained molecular dynamics: Investigating cationic surfactant / organic anion systems

Simple ammonium cationic surfactants exhibit a varied morphology depending on the carbon tail length and counter-ion that they are coupled with. For example, for ammmonium bromide pairs, the critical micelle concentration varies regularly with length, and worm-like micelles (WLM) are produced by some, while others will only give spherical micelles. Hydrophobic organic counterions such as benzoate and aminobenzoate affect both the CMC and the morphology of these cationic surfactants when compared to their bromide counterparts. Here we utilize Martini Coarse-grained methods to simulate these differences and compare them to experiment. Dry Martini2 simulations are used at low concentration in order to test a model tetradecyltrimethylammonium bromide (TTAB) cationic surfactant against the experimental CMC with very good agreement. Dry and Wet Martini simulations are used to investigate the CMC and morphology of TTA + benzoate (BZO) and 2-aminobenzoate.

About the speaker

Dr. Mike McCallum has worked at Pacific since 1994. He obtained his BS at Michigan State University in 1988, and his PhD at UC Berkeley in 1994.