Controlled synthesis of cyclic helical polyisocyanides and bottlebrush polymers using a cyclic alkyne-Pd(ii) catalyst

Cyclic polymers have very unique structure and properties, and thus have drawn intense research attention. However, controlled synthesis of cyclic polymers with predictable molar mass and narrow distribution is still a challenging task. In this study, we developed a novel cyclic catalyst that initiates the ring-expansion polymerisation of isocyanides, producing a series of cyclic helical polymers with predictable molecular weight and low dispersity. Interestingly, the ring-expansion polymerization of the isocyanide macromonomers gives well-defined cyclic bottlebrush polymers. The cyclic topology was demonstrated using transmission electron microscopy.

Automated summary

Cyclic polymers have unique structure and properties, which have attracted significant research attention. However, controlled synthesis of cyclic polymers with predictable molar mass and narrow distribution remains challenging. In this study, a novel cyclic catalyst was developed to initiate the ring-expansion polymerization of isocyanides, leading to the synthesis of cyclic helical polymers with predictable molecular weight and low dispersity. Interestingly, well-defined cyclic bottlebrush polymers were also obtained by the ring-expansion polymerization of isocyanide macromonomers, as confirmed by transmission electron microscopy.