Abstract4‐(1,3‐Dithia‐2‐thioxocyclopenthyl)methacrylate (TCMA), containing the five‐membered trithiocarbonate moiety, was prepared from glycidyl methacrylate (GMA) through 2,3‐epithiopropyl methacrylate (ETMA). At first step, GMA was converted to ETMA by the reaction using thiourea. At second step, ETMA was reacted efficiently with carbon disulfide in the presence of a catalytic amount of 1,2‐dimethyltetrahydropyrimidine to give TCMA. The polymerization of TCMA proceeded under standard radical conditions to give the polymeric TCMA in 94% yield. The copolymerizations of TCMA with ethyl acrylate (EA) or acrylonitrile (AN) were conducted by changing the feed molar ratios of the monomers, in which the corresponding copolymers were obtained in over 83% yields. In addition, the obtained polymers showed the high values of refractive index over ca. 1.6 due to the presence of the cyclic trithiocarbonate structure.

1‐Benzocyclobutenyl methacrylate‐bearing methacrylate (BCBMA) backbone has been synthesized, and radical polymerization of the monomer was performed by utilizing 2, 2′‐azobisisobutyronitrile (AIBN) as initiator to result poly‐BCBMA. Differential scanning calorimetry (DSC) measurement of the derived poly‐BCBMA revealed the lowering of thermal isomerization temperature from that of nonsubstituted benzocyclobutene. The thermal decomposition temperature of BCBMA before and after thermal treatment was confirmed by thermogravimetric analysis (TGA). The results of the TGA observation did not show significant difference in both 5% and 10% weight loss temperature (Td5 and Td10). This result suggests that the thermal conversion of the poly‐BCBMA to the networked polymer take place without thermal decomposition of the main chain based on the methacrylate framework. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2175–2180