EQUILIBRIUM BEHAVIOR OF CONFINED TRIBLOCK COPOLYMER FILMS

Using a two-dimensional self-consistent field calculation, we determin e the equilibrium morphology of thin films of ABC triblock copolymers confined between hard, smooth plates. The B segment is chosen to be th e central block and all the blocks are incompatible. The chains microp hase-segregate into a lamellar phase, with the stripes either perpendi cular or parallel to the walls. When all the monomer-surface interacti ons are identical, the perpendicular orientation has the lowest free e nergy. When a repulsion is introduced between the surface and the A an d C monomers, the surface interactions further stabilize the perpendic ular orientation. At strong surface interactions, the morphology of th e perpendicular structure is controlled by the overall thickness of th e molten layer. In comparing diblocks to triblocks as candidates for f orming laterally patterned films, our work indicates that triblocks po ssess distinct advantages over diblocks. First, no special effort need s to be taken to establish neutral surfaces. Second, the film does not have to be confined between two substrates. Thus, triblocks can be us ed to fabricate patterned polymer surfaces, which can be used for nove l optical or electronic applications.