Effect of chain architectures on the segregation degree of block copolymers

The design of polymer architectures provides a possible route for lowering the domain spacing of block copolymers in the application of directed self-assembly (DSA). However, the change of segregation degree is always coupled with that of domain spacing. Therefore, we rescale the segregation degrees of different multiblock copolymers with reference to that of AB diblock using self-consistent field theory (SCFT), including [AB]_n linear multiblock, A_nB_n multi-arm star and A_d,nB_d,n dendron-like, such that their density profiles of the lamellar morphology are consistent. Then we compare the lamellar periods of these different copolymers under the condition of equivalent segregation degrees. We find that the star and dendron-like architectures can significantly lower the domain spacing relative to that of AB diblock, especially when the arm number or the generation number is large. Our work presents a simple scheme for quantitatively quantifying the reduction of domain spacing of a specific multiblock architecture relative to that of AB diblock and also provides a useful guide for the application of directed self-assembly.