Langmuir monolayers with internal dipoles: Understanding phase behavior using Monte Carlo simulations
| Autor: | Christopher B. George, Igal Szleifer, Mark A. Ratner |
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| Rok vydání: | 2010 |
| Předmět: |
Steric effects
Canonical ensemble Phase transition Condensed matter physics Chemistry Monte Carlo method General Physics and Astronomy Molecular Dynamics Simulation Phase Transition Condensed Matter::Soft Condensed Matter Surface-Active Agents Dipole Models Chemical Chemical physics Phase (matter) Monolayer Molecule Physical and Theoretical Chemistry Monte Carlo Method |
| Zdroj: | The Journal of Chemical Physics. 132:014703 |
| ISSN: | 1089-7690 0021-9606 |
| DOI: | 10.1063/1.3280389 |
| Popis: | A coarse-grained, rigid-rod model that includes steric interactions and an internal dipole is used to study monolayers of surfactant molecules tethered to a flat interface. Monte Carlo simulations are performed in the canonical ensemble for a range of high-density configurations with varying degrees of dipole strength. Both a melting transition and a tilting transition are observed, and the dependence of the transitions on the surfactant molecules' internal dipoles is examined. Simulation results indicate that at high packing densities, the monolayers exist in a frustrated state due to dipole-dipole repulsions and steric interactions. Tilting of the surfactant molecules increases the magnitude of the dipole-dipole attractions and lowers the overall system energy, but is limited by steric repulsions. In simulations with higher dipole strengths, the melting and tilting transitions are found to be coupled. The formation of nanodomains with increased collective tilt and positional order in these systems suggests a possible mechanism for the coupling. |
| Databáze: | OpenAIRE |
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