Synthesis of Cross-Linkable Norbornenyl Copolymers via ROMP for Fabricating Cyclic Olefin Vitrimers

Dynamically cross-linked polyolefins represent a sustainable and high-performance polyolefin material that attracts great attention. In this work, a series of cross-linkable norbornenyl copolymers with tunable acetoacetate-terminated comonomer compositions are successfully synthesized via ring-opening metathesis polymerization (ROMP). Furthermore, the resulting cross-linkable norbornenyl copolymers can be cured with the primary amine cross-linker to form vinylogous urethane (VU) containing cyclic olefin vitrimers, providing opportunities for norbornenyl copolymers with enhanced properties. Our results demonstrate that tailoring the constitutional unit of linear copolymers is a viable strategy for designing vitrimers with tunable cross-linking density, which can be used to regulate thermomechanical properties markedly. Moreover, evidence manifests that the cross-linking density and free amine groups play vital roles in the dynamic properties of VU-based cyclic olefin vitrimers.