Multiple lateral length scales in phase-separating thin-film polymer blends

The interplay of phase separation, preferential wetting, and capillary inst ability in thin-film polymer blends is investigated using composition-profi ling and surface-imaging techniques. The phase-separating films exhibit a u nique morphology with two evolving lateral length scales at both the free f ilm surface and the interface between the wetting and nonwetting layers. Th e short-wavelength mode shows power-law growth at both the free film surfac e and the interface, but with a smaller growth exponent at the surface, imp lying slower kinetics. The long-wavelength mode shows two power-law growth regimes separated by a plateau.