SURFACE-INFLUENCED PHASE-SEPARATION IN ORGANIC THIN-FILMS ON DRYING

Kinetics of phase separation at the air/polymer interface in a binary polymer mixture on evaporation of common solvent is studied. The later al dimension of the highly anisotropic, pancake-like, minority phase i ncreases with a growth exponent of 2/3, identical to ''late-stage'' gr owth under (classical) thermal quench at interface. The ''wetting-laye r'' formed at the surface is directly visualized using atomic force mi croscopy. In contrast to the thermal quench, during drying the kinetic s depends on the initial condition (i.e., initial concentration, c(0)) that is resealed to obtain a master curve.