Trimethacrylate and dimethacrylate with rigid adamantane-like cores were synthesized from myo-inositol orthoester, and their radical homopolymerization and copolymerization with methyl methacrylate (MMA) were investigated. The radical homopolymerization of trimethacrylate yielded a networked polymer with higher thermal stability than that of a networked polymer synthesized by radical homopolymerization of 1,3,5-cyclohexanetriol-derived trimethacrylate, demonstrating the effect of adamantane-like core rigidity on the increase in thermal stability. Further, dimethacrylate underwent cyclopolymerization, forming a macrocyclic structure in the repeating unit, as the two methacrylate groups were oriented axially from the rigid orthoester-core and thus located close to each other. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2411-2420