Reordering transitions during annealing of block copolymer cylinder phases

摘要: While equilibrium block-copolymer morphologies are dictated by energy-minimization effects, the semi-ordered states observed experimentally often depend on details of ordering pathways and kinetics. Here, we explore reordering transitions in thin films cylinder-forming polystyrene-block-poly(methyl methacrylate). We observe several transient as order towards horizontally-aligned cylinders. In particular, there is an early-stage reorganization from randomly-packed cylinders into hexagonally-packed vertically-aligned cylinders; followed a reorientation transition vertical to horizontal cylinder states. These thermally activated. The growth grains within otherwise morphology proceeds anisotropically, resulting anisotropic final state. size, shape, anisotropy influenced history; for instance, faster heating rates reduce grain anisotropy. results help elucidate aspects pathway-dependent films.