Two different oxanorbornene monomers were prepared and copolymerized with butyl-functionalized oxanorbornene monomer through the ring-opening metathesis polymerization. The resulting polymers were then subjected to the aminolysis reactions with propylamine (PA) in the presence of methyl acrylate (MA) to capture, in situ, the latent thiol. It was found that the polymer, in which the thiolactone unit is close to the polymer backbone, did not undergo an efficient aminolysis reaction even an excess amount of PA was utilized, while the other polymer, in which the thiolactone unit away from the polymer backbone, did efficiently undergo aminolysis reaction even PA was used in low amounts. Besides, a variety of primary amine compounds along with MA were reacted with the polymer, in which the thiolactone group away from the polymer backbone, to test their reactivity toward the aminolysis reactions. All modified polymers were characterized by using conventional instruments such as gel permeation chromatography, nuclear magnetic resonance, and differential scanning calorimetry. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2145-2153