Self-consistent field theory of directed self-assembly on chemically prepatterned surfaces

We use self-consistent field theory to investigate the self-assembly of AB diblock copolymers on chemically patterned substrates. The striped substrates consist of attractive domains alternating with neutral ones. Using our simulations, we observe the formation of different self-assembled morphologies in the polymer film and compute their formation free energy for various pattern widths and wetting conditions. We found that perpendicular lamellae are best formed when the A-attractive stripes have a width near half the natural lamellar period in bulk, but lamellar structures with wide bases are also formed in wide stripes. We also computed the formation energy of isolated dislocations and found that the energy cost is ≈ 50-110kT for ±15nm deviations from optimal commensurability conditions.