Unconventional Phase Behaviors of Linear-Dendritic Copolymer due to Extremely High Frustration*

Among the various ordered structures formed by the self-assembly of block copolymer, spherical phases occupy relatively minor regions in the phase diagram. Some new spherical phases, e.g. Frank-Kasper phases, can only be obtained in a wide region of spherical phases. Several mechanisms have been established to expand the spherical region thus stabilizing the Frank-Kasper phases, while the effect of these mechanisms is still limited. Aiming to widen the phase regions of these desired new spherical phases drastically, we design a kind of linear-dendritic block copolymer and investigate its self-assembly behaviors by the self-consistent field theory (SCFT). With the optimized control parameters, the spherical phase region is expanded to be overwhelming in the phase diagram, reaching the volume fraction of 0.7, which means that the spherical domain is formed with the major component. Along with the exploration of many exotic new phases, this renews our insight into the intricate mechanism of the self-assembly of block copolymer.