Hetero-structure of ABC triblock copolymer thin film on polymer-coated substrate

The morphology and the phase diagram of the ABC block copolymer on the polymer-coated substrate were studied by using the self-consistent field theory. Due to the asymmetric surfaces for the block copolymer thin film, the rich hetero-structures occur, which are the combination of two different microstructures, such as perforated lamellar and lamellar phase (PL + L), cylindrical and lamellar phase (C + L). The phase diagrams were constructed for the identical interaction parameters case and the non-frustrated case. The effect of the film thickness is also considered at the fixed grafting density. Comparing the results, we found that the essence of the variation of the grafting density is the change of the effective film thickness in most cases. The relationship between the grafting density and the film thickness is constructed. Our results offer another way to tailor the phase behavior of the block copolymer thin film and obtain the hetero-structures on nanoscale.