Regioselective ring-opening metathesis polymerization of limonene oxide substituted cyclooctene: The highly functional ethylene/vinyl ester copolymers

We present a new cyclooctene monomer with abundant biorenewable limonene oxide as side group via simple esterification, which could be polymerized by ring-opening metathesis polymerization (ROMP) using Hoveyda-Grubbs second-generation catalyst (H2) to afford polymer with remarkably high head-to-tail regioregularity and high trans-stereoregularity, as well as precisely placed ether branches on every eighth backbone carbon. Due to the presence of easily functional oxirane in limonene oxide side chain, the polymer can be efficiently modified by thiol, or dibutyl phosphate that shows impart flame-resistant property, even bearing pendent cyclic carbonate groups by CO2 insertion catalyzed by tetrabutylammonium bromide. In all cases, the main chains of the polymer remain intact. Differential scanning calorimetry (DSC), thermal gravimetric analyzer (TGA) and the microscale combustion calorimeter test (MCC) were used to study the thermal properties and flame retardancy.