Size asymmetry in diblock copolymers of cylindrical morphology in thin films

We calculate the free energy of an AB diblock copolymer thin film of cylind rical morphology under confined geometry and find that the size of the cyli nder can be asymmetric, depending on the film thickness and surface tension . The size of the cylinder right above the surface is slightly smaller than that of the other cylinders. The equilibrium period in this thin film is d ifferent from that in the bulk because of the surface effect. The tendency toward asymmetry diminishes as the film thickness increases and the interfa cial tension between the major block (A) and the substrate decreases. (C) 2 001 John Wiley & Sons, Inc.