Detailed knowledge of the self-assembly and phase behavior of pH-sensitive surfactants has implications in areas such as targeted drug delivery. Here we present a study of the formation of micelle and bilayer from lauric acids using a state-of-the-art simulation technique, continuous constant pH molecular dynamics (CpHMD) with conformational sampling in explicit solvent and the pH-based replica-exchange protocol. We find that at high pH conditions a spherical micelle is formed, while at low pH conditions a bilayer is formed with a considerable degree of interdigitation. The mid-point of the phase transition is in good agreement with experiment. Preliminary investigation also reveals that the effect of counterions and salt screening shifts the transition mid-point and does not change the structure of the surfactant assembly. Based on these data we suggest that CpHMD simulations may be applied to computational design of surfactant-based nano devices in the future.
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Research Article| November 21 2012
Atomistic simulations of pH-dependent self-assembly of micelle and bilayer from fatty acids
Brian H. Morrow;
Peter H. Koenig;
Brian H. Morrow, Peter H. Koenig, Jana K. Shen; Atomistic simulations of pH-dependent self-assembly of micelle and bilayer from fatty acids. J. Chem. Phys. 21 November 2012; 137 (19): 194902. https://doi.org/10.1063/1.4766313
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