Two new monomers, cis-(2-phenyl-1,3-dioxan-5-yl) methacrylate (CPDM) and trans-(2-phenyl-1,3-dioxan-5-yl) methacrylate (TPDM), have been synthesized. The stereochemical configuration in both monomers was unequivocally assigned by correlation H-1-C-13 NMR experiments. The radical polymerization reactions of both monomers were studied by ultraviolet spectroscopy and electron paramagnetic resonance spectroscopy to determine the polymerization rate parameter k(p)/k(t)(1/2) and the absolute propagation and termination rate constants (k(p) and k(t)) at different temperatures. The values of k(p)/k(t)(1/2) lie in the range 0.40-0.55 L-1/2/(mol(1/2) s(1/2)) for CPDM and 0.29-0.37 L-1/2/(mol(1/2) s(1/2)) for TPDM at temperatures between 45 and 70 degreesC, showing that the polymerization rate of the cis monomer with the substituents in equatorial-axial positions on the dioxane ring is higher than that of its trans counterpart with the phenyl and ester residue in equatorial positions on the dioxane ring. Using EPR measurements of the polymer radical concentrations, similar values for hp were obtained for both trans and cis monomers, whereas the termination rate constant of the trans monomer was about twice that of the cis monomer at the same temperature.