Effect of χN and underlayer composition on self-assembly of thins films of block copolymers with energy asymmetric blocks

摘要: Many high χ block copolymer (BCP) systems often have one block which shows a strong preference to wet the free interface at the top of the film. This property makes it difficult to form vertically aligned lamellae which are desired for many directed self-assembly (DSA) applications. To better understand this behavior, simulations of thin films of BCPs were carried out using a coarse-grained molecular dynamics (MD) model. The property that leads one block to preferentially wet the free interface over the other is a difference in cohesive energy density (CED) between the two blocks. Our simulation allows for the systematic variation in the CED of each block to investigate how the magnitude of these differences affects self-assembly behavior. BCPs with no CED differences between the blocks show large ranges of underlayer compositions where vertical lamellae will form that are minimally affected by changing χ of the …