Efficient synthesis of trefoil-shaped tricyclic polymers by a ROMP-based blocking-cyclization technique

Cyclic polymers have unique physical properties and attract extensive attention, but the precision synthesis of complex cyclic polymers is a challenging subject. Herein, by using a polymeric ladderphane with six living ends as the initial motif, complex trefoil-shaped tricyclic polymers were precisely synthesized by a ring-opening metathesis polymerization-based blocking-cyclization technique in a simplified process, where three macromolecular rings consisting of multiple repeating units were covalently interconnected at a single junction point, and the ring size was readily regulated by varying the feed ratio of monomers. The topological structures and physical properties of trefoil-shaped tricyclic polymers were fully characterized. Importantly, the molecular topology of trefoil-shaped tricyclic polymers was clearly observed. Therefore, this work provides an effective strategy for the synthesis of complex cyclic polymers.