Methyl alpha-[2,2-bis(carbomethoxy)ethyl]acrylate [M(DM)EA], which was synthesized by the reaction of methyl alpha-(bromomethyl)acrylate and dimethyl malonate in the presence of triethylamine at room temperature, was found to readily polymerize and copolymerize to high molecular weight, although the presence of a considerable steric hindrance was expected. The propagating polymer radical from M(DM)EA was detected and quantified by ESR spectroscopy during bulk polymerization. The absolute rate constants of propagation and termination (k(p) and k(t)) for M(DM)EA at 60 degrees C, k(p) = 4.0 L/(mol s) and k(t) = (3.8-4.2) x 10(4) L/(mol s), which were evaluated using the concentration of the propagating radical at the steady state, are extraordinarily smaller than those for methyl methacrylate (MMA) by 2 and 3 orders of magnitude, respectively. The balance of the propagation and termination rates allows the polymer formation because the steric effect of the alpha-substituent suppresses the propagation and termination simultaneously. A relatively low ceiling temperature of M(DM)EA, which was estimated to be ca. 90 degrees C in bulk, reduced the polymerization rate at high temperatures. The steric hindrance was also observed in the copolymerization of M(DM)EA with styrene and MMA. It is concluded that M(DM)EA is one of the polymerizable acrylates bearing an alpha-substituent exhibiting significant steric hindrance.