Institute of Fundamental Technological Research Polish Academy of Sciences CONDITIONS FOR CREATING THIN LIQUID LAYERSAT THE CONTACT SURFACE OF TWO OTHER LIQUIDS Agnieszka Słowicka Zbigniew A. Walenta
Oil Oil Water Oil Water Aim- Nanomaterials of structure as shown The emulsion with thin layers of third substance at the surface between oil and water The structure of nanomaterial after removing water and oil
Molecular Dynamics Simulation Liquid – an ensemble of molecules Interaction between molecules Electrostatic interaction van der Waals interaction Coulomb potential Lennard - Jones potential The program „Moldy” by Keith Refson used for simulation.
Models of molecules and interactions Molecule of water Molecule of oil Molecule of the third fluid Diagram of the Lennard-Jones potential
Parameters of the Lennard-Jones potential Oil Water O + + H H 180 amu 18 amu
t = 0 ps t = 9 ps t = 13 ps Molecules of water = 1000 o Diameter of the droplet ~ 32 A diameter of oil droplet Oscilation period = 26 ps ~ average speed of molecules Formation of water droplet in vacuum
Molecules of water = 7000 Molecules of oil = 1000 Diameter of oil droplet ~ t = 0 ps t = 5 ps t = 13 ps Simulation of emulsification process Temperature = 300 K
Temperature = 300 K Molekules of water = 2614 Molekules of oil = 257 Molecules of soap = 252 o 20 A Diameter of oil droplet ~ Simulation of three liquids t = 0 ps t = 48 ps t = 123 ps
Conclusions • The molecular dynamics seems to be the best tool to simulate physical processes on a nanoscale in liquids. • Formation of water droplet in vacuum and oil droplet in water have been simulated successfully. • The addition of soap, expected to remain at the surface of oil, leads to destruction of oil droplets. • Now we look for other substances which would stay at the surface of the droplets and would not destroy them.