Phase Behavior of Linear-Star Topology-Transformable Block Copolymers

Linear-star topology-transformable copolymers are a new class of block copolymers employing freely sliding rotaxane structures instead of covalent bonds to connect different blocks, which can dynamically change their topology according to the environment. We introduce a sliding degree of freedom to describe the adaptive self-sorting of molecular topology and carry out a theoretical investigation using the Gaussian chain model and random phase approximation. By comparing the spinodal of topology-transformable copolymers with the corresponding nonsliding branched copolymers, we show that the sliding degrees of freedom can shift the spinodal point to be lower than that of the corresponding linear diblock copolymers. We further demonstrate that variation of sliding degrees of freedom is related to the long-range correlation between different polymer components, and the correlation between branched chain segments and the different segments of the main chain exhibits universal behavior.