1. Surfactant at Oil / Water Interface – Comparison with Simulation
Development of a Density Functional Theory for Copolymer and Surfactant Interfacial Properties and Microstructure
Walter G. Chapman, Rice University, Houston, TX
Our group is developing a novel density functional theory for multi-scale modeling of complex fluids and will apply the theory to several critical problems related to self-assembled systems. The research work has shown great promise for predicting interfacial properties and structure of surfactants and copolymer solutions and blends. The work is of particular interest to Dow Chemical Company and Sandia National Laboratory to model performance polymers and precursors to nanomaterials.
Simulation - Smit, B., et al. J. Phys. Chem. 1991, 95,
Results show excellent agreement with molecular simulation results for the interfacial tension and the surfactant structure in the interface (see figure upper right). Results show 2-tailed surfactants with a fixed number of tail segments produce greater reductions in interfacial tension the more asymmetric the distribution. Equilibrium microstructure results also suggest the amphiphile collapses on the interface rather than extending into the solvent.
Another application shows predictions of the structure of a lipid bilayer in comparison with MD simulation results (see figure lower right). The density functional theory accurately matches simulation results.
Lipid Bilayer from DFT compared with MD Simulations from Frischnecht and Frink