Chiral amplification induced by self-assembly of different aggregation states in liquid crystal block copolymer films with chiral response

Abstract

Chiral films with a high optical asymmetry show substantial potential in organic optoelectronics and other chiroptical fields. However, the fabrication of chiral films with high circular dichroism and chiral response remains challenging. Herein, hierarchical nanostructures with controllable optical asymmetry and chiral response were formed in a liquid crystalline block copolymer film (LC-BCP) induced by the enantiomers dibenzoyl tartaric acid (DiBTA) or dibenzyl ester tartaric acid (DiBETA). A high chiral amplification was achieved with an asymmetry factor (g_abs) of up to 0.079 when DiBTA was used, which was 10-fold larger than when DiBETA was used. The difference in g_abs was verified by the different stacking modes between the exogenous chiral molecules and LC-BCP. Specifically, DiBTA caused a J-aggregation self-assembly, while DiBETA resulted in an H-aggregation self-assembly. Additionally, the obtained chiral films presented an excellent chiral response to photo and thermal stimuli, allowing the chiral switch rapidly and reversibly. This study provides a pathway to the design of chiral film materials with high optical activity and stimuli response for potential applications in diverse fields such as chiral recognition, storage, metamaterials, and so on.