Luminogenic polymers with aggregation-induced emission characteristics

Aggregation-induced emission (AIE) is a newly developed phenomenon that is exactly opposite to the aggregation-caused emission quenching effect observed with some conventional luminophores. The AIE phenomenon was first realized in propeller-like small molecules and now has extended to polymeric systems. In this review, we summarize the recent progress on the preparation of luminogenic polymers with AIE or aggregation-enhanced emission (AEE) characteristics, which are generally prepared by attaching AIE-active luminogens, such as tetraphenylethene and silole, as pendants to the polymer backbones or utilizing them as skeletons for main chain polymers. An AIE phenomenon was observed in succinic anhydride-containing nonconjugated polymers bearing no luminogens, presumably due to the agglomeration of carbonyl groups. The AIE/AEE-active polymers show unique properties, such as emission superquenching, high and tunable light refractivity, and aggregation-enhanced two-photon excited fluorescence, and have found potential applications as fluorescent sensors, biological probes, and active layers for the fabrication of light-emitting diodes.