Self-consistent Field Theory Simulations of the Phase Behavior of Tapered Diblock Copolymers

Phase diagrams of tapered and inverse-tapered diblock copolymers were computed by self-consistent field theory. These copolymers consist of three ``blocks'': a pure A block, a linear gradient ``block'' that is either A to B (tapered) or B to A (inverse-tapered), and a pure B block. This composition was approximated using a multi-block model in which the tapered region consisted of alternating A and B blocks of appropriate size to approximate the gradient. Phase diagrams were produced for varying sizes of the tapered region, showing a shift of the ordered phases to higher $\chi N$ for larger tapered regions (and higher still for inverse-tapered systems), while preserving non-lamellar phases in some cases.