Accurate Detection of the Structural Features of Liquid Crystalline Block Copolymer Cylindrical Micelles via Aggregation-Induced Emission

Aggregation-induced emission luminogens (AIEgens) possess a distinctive photoluminescence (PL) mechanism characterized by their exceptional sensitivity to changes in the microenvironment. This unique feature allows the effective correlation of macroscopic fluorescence intensity with the variations in molecular packings, which is crucial for real-time monitoring of polymer chain dynamics in both bulk and micellar assemblies. In the current study, we synthesized two fluorescent liquid crystalline (LC) block copolymers (BCPs) of similar molecular weights and block ratios─ one with a single tetraphenyl ethylene (TPE) moiety labeled at the end of the LC core-forming block, and the other having it randomly integrated into the corona-forming block. Both BCPs could form similar cylindrical micelles (CMs). Taking advantage of the AIE property, the critical micellization concentrations and LC phase transition temperatures of the CMs could be accurately determined. Additionally, uniform CMs with various lengths from both BCPs were prepared by using the “self-seeding” method. Their PL performance showed that despite the ordered mesogenic packing inside the micellar core and the crowded coronal chains, the compression of the core-forming chains and the stretching of the corona-forming chains remained largely unchanged and were irrelevant to their lengths. This study provides critical experimental evidence for the fundamental understanding of BCP micellar assemblies.