Novel complex nanostructure from directed assembly of block copolymers on incommensurate surface patterns

The directed assembly of a block copolymer on a chemically patterned surface may produce a well-registered novel complex nanostructure was demonstrated. When a cylinder-forming block copolymer was assembled on a chemical pattern, a 3D structure was produced that provides linear arrays of nanocylinders whose orientation is registered by the surface pattern underneath. The cylinders in the block copolymer thin film were spontaneously oriented normal to the neutral homogeneous SAM surface due to the thin-film confinement. The top-view scanning electron microscopy (SEM) showed the hexatic arrangement of cylinders, and a cross-sectional image demonstrated that the cylinders were oriented perpendicular to surface throughout the film thickness. Real-space self-consistent field (SCF) calculations used for the self-assembled morphology of block copolymers provided insights into the 3D structure inside thin films.