Soluble graphene composite with aggregation-induced emission feature: non-covalent functionalization and application in explosive detection

Abstract

Herein, a soluble graphene-based material exhibiting the aggregation-induced emission (AIE) feature was prepared for the first time via wet chemistry by the chemical reduction of graphene oxide (GO).

Covalent Functionalization of Graphene by Nucleophilic Addition Reaction: Synthesis and Optical‐Limiting Properties

“…It is known that the TPE group adopts a typical configuration owing to the aggregation‐induced emission (AIE) effect: the four propeller‐like phenyl rings undergo an active intramolecular rotation (IMR) process in the solution state to make TPE non‐emissive, whereas in the aggregated state, the restricted IMR process blocks the nonradiative decay channel, which ultimately makes TPE emissive . According to previous reports based on TPE‐containing polymers, if TPE is introduced into a polymer chain, its AIE feature is still effective . In Figure a, P1 exhibits negligible luminescence at λ =497 nm; after the addition of NaH, the emission band is redshifted to λ =561 nm, and this is accompanied by a reddish‐orange luminescence emission under a UV lamp ( λ =365 nm).…”

“…Luckily, both poly(9,9′‐diheylfluorene carbazole) (PCF) and poly[4,4′‐(2,2‐diphenylethene‐1,1‐diyl] bis[(4‐bromobutoxy)benzene carbazole] (PCT) greatly improved the dispersion stability of rGO in water medium, and the resultant rGO‐based materials showed excellent optical‐limiting behaviors . Recently, we employed three conjugated polymers containing tetraphenylethylene (TPE), carbazole, and phenyl groups for the noncovalent functionalization of rGO . Luckily, the solubility of rGO was enhanced greatly, and the rGO‐based materials were soluble in organic solvents.…”

“…This discrepancy is perhaps not only connected with the bonding (covalent or noncovalent interaction) between rGO and the polymers, but also with the microstructure of the resultant materials. The rGO‐P1 resultant material prepared by covalent functionalization has micrometer dimensions (Figure ), and these dimensions are larger than those of the material prepared by noncovalent functionalization . Furthermore, unlike the material prepared by noncovalent functionalization, no cavities are observed for the material prepared by covalent functionalization.…”

“…The functionalization is also reflected in the fluorescence spectra of P1 and rGO‐P1 (Figure ). As mentioned before, upon introducing TPE into the polymer moiety, the unlinked phenyl rings undergo an active IMR process; however, the IMR process is prohibited in the aggregation state, which ultimately blocks the nonradiative decay channel and makes the polymer have an AIE or an aggregation‐induced emission enhancement (AIEE) effect . In this article, the fluorescence spectra of P1 in the solution and aggregation states were both measured.…”

“…The fluorescent spectra of rGO‐P1 in THF and THF/H 2 O were both nearly parallel to the abscissa. The fluorescence intensity of P1 was quenched by approximately 99.5 % by the presence of rGO, and no luminescence of rGO‐P1 was observed under a UV lamp, which was different from the results obtained by noncovalent modification . This discrepancy is perhaps not only connected with the bonding (covalent or noncovalent interaction) between rGO and the polymers, but also with the microstructure of the resultant materials.…”