A facile and efficient approach for design and synthesis of organic fluorescent nanogels has been developed by using a pre-synthesized polymeric precursor. This strategy is achieved by two key steps: (i) precise synthesis of core–shell star-shaped block copolymers with crosslinkable AIEgen-precursor (AIEgen: aggregation induced emission luminogen) as pending groups on the inner blocks; (ii) gelation of the inner blocks by coupling the AIEgen-precursor moieties to generate AIE-active spacers, and thus, fluorescent nanogel. By using this strategy, a series of star-shaped block copolymers with benzophenone groups pending on the inner blocks were synthesized by grafting from a hexafunctional initiator through atom transfer radical copolymerization (ATRP) of 4-benzoylphenyl methacrylate (BPMA) or 2-(4-benzoylphenoxy)ethyl methacrylate (BPOEMA) with methyl methacrylate (MMA) and tert -butyldimethylsilyl-protected 2-hydroxyethyl methacrylate (ProHEMA) followed by a sequential ATRP to grow PMMA or PProHEMA. The pendent benzophenone groups were coupled by McMurry reaction to generate tetraphenylethylene (TPE) groups which served as AIE-active spacers, affording a fluorescent nanogel. The nanogel showed strong emission not only at aggregated state but also in dilute solution due to the strongly restricted inter- and intramolecular movement of TPE moiety in the crosslinked polymeric network. The nanogel has been used as a fluorescent macromolecular additive to fabricate fluorescent film.

A polymeric precursor strategy was developed toward precise synthesis of uniform and size-tunable hairy fluorescent carbon dots (C-dots, CDs). The strategy was achieved by (i) the synthesis of core−shell 6-arm starlike block copolymers of PGMA-b-PMMA (poly(glucosyl methyacrylate), PGMA; poly-(methyl methacrylate), PMMA), serving as a precursor using atom transfer radical polymerization (ATRP) and (ii) selective carbonization of the inner PGMA chains to generate hairy C-dots with PMMA blocks attaching on the surfaces. The resultant C-dots with tunable sizes showed blue to green fluorescence depending on the excitation, size, and concentration. The large size of the C-dots led to a significant red shift of fluorescence emission, which was attributed to enhanced intra-C-dot Forster resonance energy transfer (FRET) between the emitter homologues in a single C-dot. In addition, the FRET effect between C-dots was further confirmed by the aggregation-caused quenching characteristics and red shift of emission at high concentrations. Interestingly, different from the traditional fluorophores with photobleaching characteristics, C-dots showed recoverable photoabsorption capacity and enhanced fluorescence after the long-time exposure to UV light.