Accurate Detection of Liquid Crystalline Transitions of Cholesteryl-Containing Homopolymers via the Aggregation-Induced Emission of Tetraphenylethylene

Since the discovery of the aggregation-induced emission (AIE) phenomenon, it has been widely applied in various fields. Particularly, the emission of AIE moieties is highly sensitive to their molecular packing and very useful to reveal the chain movement of polymers in real time. Herein, we report our attempts to use tetraphenylethylene (TPE) to characterize the liquid crystalline (LC) transitions of cholesteryl-containing homopolymers by monitoring their emission intensity variations versus temperature. However, unlike similar cases aiming for other characteristics of polymers, directly blending TPE molecules into homopolymer matrices markedly disrupted the LC transition. Although the fluorescence intensity variations could decently reveal the glass transition temperature (T_g), it exhibited absolutely no sensitivity to the LC transition process. Meanwhile, if the TPE moieties were labeled onto one of the chain ends of homopolymers, the LC transition was untouched, and the transition points determined were identical to those obtained from standard techniques.