Ring-opening metathesis polymerization (ROMP) of thioether-derived oxanorbornene imide (M1) and its copolymerization with various cycloolefin comonomers such as cyclopentene (M2), cyclopent-3-en-1-ol (M3), cycloheptene (M4), and cyclooctene (M5) using Hoveyda-Grubbs second generation catalyst has been investigated. Polymerizations were performed at two different temperatures (0 and 25 degrees C) and the obtained functional poly(olefin)s were characterized by nuclear magnetic resonance H-1 and C-13 (NMR), and infrared spectroscopy as well as size exclusion chromatography, differential scanning calorimetry, and thermogravimetric analysis analyses. Additionally, the dependence of the polymer composition on the reaction temperature and monomer feed was studied with time-dependent H-1 NMR experiments. Copolymerization of M1 with a five-membered cycloolefin monomer M2 showed relatively low ROMP reactivity irrespective of the reaction conditions in comparison to M3, M4, and M5 monomers. In general, the degree of monomer incorporation into poly(olefin)s were determined in the order of M5 > M3 > M4 > M2, and that sheds light on the effect of cycloolefin ring strain energies in the ruthenium-alkylidene initiated ROMP. (c) 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019