| Abstract: |
A promising solution to address the challenges in plastics sustainability is to replace current polymers with chemically recyclable ones that can depolymerize into their constituent monomers for circular use of materials. Despite the progress, few depolymerizable polymers exhibit the excellent thermal stability and strong mechanical properties of traditional polymers. Particularly most depolymerizable polymers would undergo unintended depolymerization. Chemically recyclable polymers that are based on olefin metathesis can potentially address these issues since olefin metathesis only occurs in the presence of the corresponding catalyst and the unintended depolymerization can be prevented by removing the catalyst. However, metathesis-based depolymerizable polymers have been limited to polypentenamers—the polymers made via ring-opening metathesis polymerization (ROMP) of cyclopentene and its derivatives—which have low glass transition temperature, produce amorphous materials, and are not able to meet the needs of most plastics applications. The depolymerization of polypentanamers are enabled by the low ring strain energy of the 5-membered ring monomers; ring strain energies of other cycloalkenes are either too low for efficient ROMP or too high for depolymerization. To expand the scope of the monomers for depolymerizable ROMP polymers, we look into fusedring olefins. Our recent studies have shown that incorporating trans-cyclobutane and trans-cyclopentane at the 5,6-positions of cyclooctene can reduce the ring strain energy to a level comparable to that of cyclopentene. We will systematically investigate the structure–ring strain energy relationship in fused-ring olefins, including the size of the cyclic olefins, the size, stereochemistry and location of the additional ring as well as. |
0000-0002-4503-5026