Cross‐domain Chirality Transfer in Self‐Assembly of Chiral Block Copolymers

Chirality transfer is essential to acquire helical hierarchical superstructures from the self‐assembly of supramolecular materials. By taking advantage of chirality transfers at different length scales through intra‐chain and inter‐chain chiral interactions, helical phase (H*) can be formed from the self‐assembly of chiral block copolymers (BCPs*). In this study, chiral triblock terpolymers, polystyrene‐b‐poly(ethylene oxide)‐b‐poly(L‐lactide) (PS‐PEO‐PLLA), and polystyrene‐b‐poly(4‐vinylpyridine)‐b‐poly(L‐lactide) (PS‐P4VP‐PLLA) are synthesized for self‐assembly. For PS‐PEO‐PLLA with an achiral PEO mid‐block that is compatible with PLLA (chiral end‐block), H* can be formed while the block length is below a critical value. By contrast, for the one with achiral P4VP mid‐block that is incompatible with PLLA, the formation of H* phase would be suppressed regardless of the length of the mid‐block, giving cylinder phase. Those results elucidate a new type of chirality transfer across the phase domain that is referred as cross‐domain chirality transfer, providing complementary understanding of the chirality transfer at the interface of phase‐separated domains. The compatibility of mid‐block and chiral block is critical to the cross‐domain chirality transfer in ABC*‐type chiral triblock terpolymers. When the mid‐block is compatible with the chiral block, chirality could transfer through the mid‐domains with limited thickness. In contrast, as the mid‐block is incompatible with the chiral block, chiral interactions will be restricted, independent with the length of mid‐block.