Cyclic-hanging-multicyclic polymer synthesized by ladderphane-mediated blocking-cyclization technique for the direct visualization of cyclic macromolecular topology

Cyclic polymers have attracted a wide range of interest due to their unique physical properties; however, the synthesis of multicyclic polymers with a complex topology remains a great challenge on account of the limitations of the synthesis methods. Herein, a unique cyclic-hanging-multicyclic polymer topology was developed by a ring-opening metathesis polymerization (ROMP)-based grafting-through approach and ladderphane-mediated blocking-cyclization technique. The cyclic polythioether side-chain-contained norbornene macromonomer that was first synthesized by a ring-opening polymerization of thiirane with the ring-expansion of rhodanine, and the multicyclic polymer was then obtained by successive ROMPs of di-, mono-, and difunctional norbornene monomers, where macromonomer and monofunctional monomer were randomly copolymerized to control the cyclic chain length and side ring number. The multicyclic polymer structure was characterized and the complex chemical composition confirmed. Importantly, the cyclic molecular topology was directly visualized without a tedious post-modification process.