Cylindrical phase of block copolymers: Stability of circular configurationto elliptical distortions and thin film morphologies - art. no. 061809

We study the cylindrical phase of a diblock copolymer melt in the strong se gregation limit, and initially examine the stability of this morphology aga inst elliptical perturbations. Surprisingly, we find that an elliptical con formation of the columns has lower free energy than a circular one. The siz e of the ellipse's eccentricity depends on f, the minority block fraction. We proceed to examine the morphology of the melt when placed between two ha rd, flat surfaces. The columns can either form with their axes in the plane of the bounding surfaces (denoted parallel) or with their axes perpendicul ar to the bounding surfaces. We determine when the parallel alignment is pr eferred over the perpendicular alignment.