The Polymer Society of Korea

Abstract

This study investigates self-interrupted living polymerization (SILP) behavior in star polymers synthesized via ring-opening metathesis polymerization (ROMP). Using an in situ core-first approach, we observed an unusual decrease in molecular weight with increasing arm degree of polymerization (DP), deviating from conventional living polymerization behavior. This observation suggests a topology-driven chain transfer between arms, leading to catalyst loss and spontaneous self-termination. To enhance inter-arm chain transfer, norbornene was deliberately employed as the arm monomer. While this choice promoted inter-arm interactions, it also induced star–star coupling, which obscured the intrinsic SILP behavior. Polymerization conditions were therefore systematically adjusted to suppress star–star coupling while preserving inter-arm chain transfer processes. Under these optimized conditions, peaks corresponding to star polymers exhibiting SILP behavior and a species presumed to be polynorbornene detached from the star polymers were observed in the supernatant. These findings provide evidence for a previously unrecognized mechanism induced by the topological structure of star polymers.