Surfactant-stabilized structures in confined liquids

Grand canonical Monte Carlo simulations are used to investigate the effect of surfactant on binary Lennard-Jones mixtures confined between planar, chemically patterned surfaces. Near bulk demixing coexistence, confined binary mixtures form liquid "bridges" joining specifically patterned surface areas. The length of these bridges is restricted by the unfavorable liquid-liquid interfacial tension, and in the present paper we show that this constraint can be significantly reduced by adding surfactant to the system. This leads to very extended liquid bridges and to other structures not found in the simple two-component case. We give a qualitative discussion of the surface-surfactant -induced liquid structures and examine in detail the associated forces acting between the plates. (C) 2003 American Institute of Physics.