A cyclopolymer incorporating tetraphenylethene groups in its cyclic repeating units

Although incorporating AIEgens in versatile polymer topological structures is of high interest, cyclopolymers incorporating AIEgens have rarely been reported yet. In this work, a cyclopolymer incorporating tetraphenylethene groups in its cyclic repeating units (pTPE-dMMA) is synthesized in comparison with a linear polymer with tetraphenylethene pendant side groups (pTPE-MMA). The PLQY of pTPE-dMMA in the solid state is 50.35%, higher than that of pTPE-MMA (32.06%) in the solid state. The AIE behaviors of both pTPE-dMMA and pTPE-MMA in solutions are investigated. Because of the ring-constraint, the PL color of AIE cyclopolymer is not dependent on aggregation, while the PL intensity increases as the increased cyclopolymer concentration or aggregation. Even in an ultra-dilute solution (0.002 mg/mL), pTPE-dMMA exhibits significant AIE performance as the water fraction is increased. The enhanced AIE properties of pTPE-dMMA are ascribed to the ring constraint in the side groups and dense intra-/inter-molecular stacking. This work is useful not only for the designing novel AIE materials or fluorescent dyes, but also for understanding the structure–property–function relationships of a cyclopolymer.