The length of the polymer blocks (red and blue squiggly lines) and the strength of their interaction determine the shape of the resulting patterns in block copolymer self-assembly: (from left to right) spheres, cylinders, and lamellae (sheets).
Plan view (top) and cross-sectional (bottom) scanning electron microscope images of an inorganic nanomesh created through iterative self-assembly and infiltration synthesis.
Without blending, the size of grains (single-color regions) of a diblock copolymer with a molecular weight of 36 kilograms/mole barely changes with thermal annealing over time (top row). Blending the block copolymer with homopolymers increases the grain size and speeds up the ordering process (bottom row).
A comparison of scanning electron microscope images after solvent vapor annealing of a large block copolymer (top left) and the same copolymer with added homopolymer (top right) shows that the homopolymer can significantly improve pattern quality. The bottom image is a cross-sectional image of the top right sample.