Homochiral Evolution from Self-Assembly of Chiral Block Copolymers

Abstract

A block copolymer containing a chiral block is referred to as a chiral block copolymer, which can form a helical phase (H*) in diblock copolymers and an alternating gyroid phase (G^A) in triblock terpolymers with controlled chirality from self-assembly, as evidenced by electron tomography. Polylactide-containing chiral block copolymers can be used as a representative system for the investigation of homochiral evolution from molecular chirality examined by electronic circular dichroism (ECD) to conformational chirality examined by C═O vibrational circular dichroism (VCD), and finally to phase chirality characterized by electron tomography, with C–O–C VCD providing insight into interchain chiral interactions. The intra- and interchain contributions should be evaluated in the context of the specific molecular structure and sample conditions. By taking advantage of noncovalent chirality induction, it is feasible to introduce a chiral bias by associating a chiral dopant with an achiral block, giving H* with controlled chirality from an achiral block copolymer. This Viewpoint highlights the fundamental principles, providing perspectives on the design of chiral soft materials for device applications.