Fundamental Insights into Crystallization and Microphase Separation of Conjugated Block Copolymers

Conjugated polymer-based block copolymers (BCPs) are important materials as they incorporate the optoelectronic properties of conjugated polymers and unique microphase-separated properties of BCPs. The ability to tailor the two basic phase behaviors (crystallization and microphase separation) within conjugated BCPs is highly desirable to not only control their physical properties, but also strengthen the fundamental understanding of rod-like BCPs. However, the crystallization of semirigid conjugated polymers has not been well elucidated compared to traditional flexible polymers. Moreover, the phase behaviors of conjugated BCPs are much less understood than those of classical coil-coil BCPs from both theoretical and experimental aspects. In this Viewpoint we begin with a brief introduction of chain stiffness and the crystallization of conjugated polymers. After introducing the phase behaviors of BCPs including coil-coil, rod-coil, and rod-rod types, we discuss recent advances in the interplay and competition between crystallization and microphase separation within conjugated BCPs, as well as their applications in organic electronics. Finally, ongoing challenges and future perspectives will be discussed.