We study the interplay of wetting and phase separation in an unstable binary mixture $\mathrm{}\left(\mathrm{AB}\right)\mathrm{}$ with off-critical composition, placed in contact with a surface which prefers the component $A.\mathrm{}$ We consider surface potentials $V\left(z\right)\mathrm{}\sim z^{-n},$ where z is the distance from the surface, and present analytical arguments and detailed numerical results to elucidate wetting-layer kinetics for arbitrary mixture compositions. If the preferred component is the minority phase, the wetting-layer thickness exhibits a potential-specific behavior at early times $\tau ,$ $R_1\sim {\tau }^{1/(n+2\mathrm{})\mathrm{}},$ before crossing over to the universal growth law, $R_1\sim {\tau }^{1/3}.$ On the other hand, if the preferred component is the majority phase, there is a crossover from potential-specific growth (as before) to a slower growth regime.

• Received 24 July 2002

DOI:https://doi.org/10.1103/PhysRevE.66.061602