Recent Advances in Fluorescent Polymers with Color-Tunable Aggregate Emission

Abstract

The modulation of fluorescence properties of light-emitting molecules, especially in solid or aggregate states, is crucial for their practical applications. Polymeric systems offer flexible structural design and solution-processing abilities, affording versatile platforms for achieving color-tunable aggregate fluorescence, especially for those with welldefined structures obtained by controlled polymerization. Meanwhile, the emergence of aggregation-induced emission (AIE) and thermally activated delayed fluorescence (TADF) concepts has revolutionized the field of light-emitting materials, including fluorescent polymers. This Review focuses on the recently developed polymer systems that have realized the fine-tuning of aggregate emissions. It delves into various color-tuning mechanisms, exploring molecular interactions such as dye−dye interactions, charge transfer, energy transfer, and the polymeric microenvironment. Special attention is given to through-space charge transfer (TSCT) and unconventional Forster resonance energy transfer (FRET), which have garnered significant interest recently. We aim to offer valuable insights into molecular structural design from the perspective of fluorescence color-tuning and eventually provide an outlook on potential directions for future research in this field.

Bilayer Asymmetric Hydrogels with Simultaneous Changes in Fluorescence Brightness and Shape Enabled by AIEgens

“…Therefore, incorporating luminescent units into the hydrogel matrix and producing changes in brightness when the hydrogel network swells or shrinks have become an urgent issue that we need to consider. The aggregation-induced emission (AIE) effect means that AIEgens are not emitted as isolated species in good solvents but are highly emitted as aggregates in poor solvents, − which is thought to be due to the restriction of intramolecular motion effects. , The strong emission of AIEgens in aggregated, solid, or confined states makes it suitable for application in solid hydrogel systems. , Therefore, many stimulus-responsive materials based on AIEgens have been developed and applied, − and some of them will change their fluorescence color or brightness when stimulated, − which provides the basis to build intelligent light-emitting driving materials.…”