Forces between chemically patterned plates immersed in binary liquid mixtures

Grand canonical Monte Carlo calculations are used to investigate the phase behavior of a binary mixture of Lennard-Jones particles confined between planar, parallel, chemically patterned plates. Attention is focused on the influence of surface-induced transitions on the net force acting between the plates. In addition to the stable and metastable bulk states that play a crucial role for homogeneous surfaces, for certain patterns and surface separations a bridge phase analogous to that recently reported for one-component systems is observed. It is found that bridge phase formation leads to strongly attractive plate-plate forces that are equal in magnitude to those observed for homogeneous surfaces. The significance of our results for the interaction and behavior of nonuniform macroparticles in solution is discussed. (C) 2002 American Institute of Physics.