Aggregation‐Induced Emission Boosting the Study of Polymer Science

Abstract

Dedicated to Professor Daoben Zhu on the occasion of his 80th birthday The past one hundred years have witnessed the great development of polymer science. The advancement of polymer science is closely related with the development of characterization techniques and methods, from viscometry in molecular weight determination to advanced techniques including differential scanning calorimetry, nuclear magnetic resonance, and scanning electron microscopy. However, these techniques are normally constrained to tedious sample preparation, high costs, harsh experimental conditions, or ex situ characterization. Fluorescence technology has the merits of high sensitivity and direct visualization. Contrary to conventional aggregation-causing quenching fluorophores, those dyes with aggregation-induced emission (AIE) characteristics show high emission efficiency in aggregate states. Based on the restriction of intramolecular motions for AIE properties, the AIE materials are very sensitive to the surrounding microenvironments owing to the twisted propeller-like structures and therefore offer great potential in the study of polymers. The AIE concept has been successfully used in polymer science and provides a deeper understanding on polymer structure and properties. In this review, the applications of AIEgens in polymer science for visualizing polymerization, glass transition, dissolution, crystallization, gelation, self-assembly, phase separation, cracking, and self-healing are exemplified and summarized. Lastly, the challenges and perspectives in the study of polymer science using AIEgens are addressed.

Chitosan Surface-Modified PLGA Nanoparticles Loaded with Cranberry Powder Extract as a Potential Oral Delivery Platform for Targeting Colon Cancer Cells

“…CBPE’s entrapment efficiency values increased as the L/G ratio decreased. The %EE could be attributed to the glass transition temperature ( T g ) of the PLGA polymer, which is the temperature at which an amorphous polymer acquires the glassy-state characteristics of stiffness, brittleness, and rigidity upon cooling [ 44 ]. The reported T g for PLGA 50:50 and PLGA 85:15 are 45–50 °C and 50–55 °C, respectively, which indicates that as the L/G ratio grows, T g increases [ 45 ].…”

Survey of Recent Advances in Molecular Fluorophores, Unconjugated Polymers, and Emerging Functional Materials Designed for Electrofluorochromic Use

“…The fluorescence yield increases because the restricted intramolecular motion deactivation pathways of the excited state are no longer active. Tetraphenylethene ( TPE , Figure 8 ) is the most widely used AIE fluorophore [ 104 , 105 , 106 ]. It fluoresces minimally in solution, but its emission is significantly increased when aggregated in solution.…”

Aggregation-Induced Emission Polymers via Reversible-Deactivation Radical Polymerization

“…Researchers have attempted to rationalize such observations and among the many proposed explanations, the restriction of intramolecular motion (RIM) theory took the throne. [13][14][15] This mechanism comprises two parts: restriction of intramolecular rotation (RIR) (Figure 1B ) and restriction of intramolecular vibration (RIV) (Figure 1C ). This theory assumes most molecules that underwent ACQ instead of AIE, possess highly coplanar aromatic rings in them, while AIE molecules adopt a "propeller-shaped" structure where the aromatic rings represent the "rotors", able to rotate freely in the molecular state and promote energy transfer among molecules, hence generating a new path for non-radiative decay.…”

“…Copyright 2001, Royal Society of Chemistry (B ) Restriction of Intramolecular Rotation (RIR) effect of 1,1,2,2-tetraphenylethene (TPE), and (C ) Restriction of Intramolecular Vibration (RIV) effect of 10,10',11,11'-tetrahydro-5,5'-bidibenzo[a,d ][7]annulenylidene (THBDBA). Adapted with permission [13]. Copyright 2022, Wiley-VCH.…”