SURFACE EFFECTS ON SPINODAL DECOMPOSITION IN BINARY-MIXTURES - THE CASE WITH LONG-RANGED SURFACE FIELDS

We present detailed numerical results for phase-separation kinetics of critical binary mixtures in the vicinity of a surface that exerts a l ong-ranged attractive force on one of the components of the mixture. W e consider surface potentials of the form V(Z)similar to Z(-n), where Z is the distance from the surface and n = 1,2,3. In particular, we in vestigate the interplay of the surface wetting layer with the dynamics of domain growth. We find that the wetting layer at the surface exhib its power-law growth with an exponent that depends on n, in contrast t o the case with a short-ranged surface potential, where the growth is presumably logarithmic. From correlation functions, we identify charac teristic length scales in directions parallel and perpendicular to the surface. We observe a regime of accelerated growth in the parallel di rection and critically examine some possible explanations for this.