Methyl alpha-(crotonyloxymethyl)acrylate (MCRMA) of which the alpha-substituted acryloyl and crotonyl groups are sterically hindered and reluctant to homopolymerize, respectively, was synthesized and polymerized. The polymerization of MCRMA primarily took place through homopolymerization of the alpha-(substituted methyl)acryloyl group to yield a soluble polymer bearing a large number of the pendant crotonyloxy groups. The ratio of the rate constants for the inter- and intramolecular additions of the propagating radical to form the linear and cyclic repeating units, respectively, indicates that this monomer exhibits an exceptionally low possibility of cyclopolymerization because of the sterically hindered intramolecular addition of the crotonyloxymethyloyl radical to the crotonyl group. Crosslinking by the reaction of the pendant double bond slowly proceeded due to an extremely low reactivity of the crotonyloxy group towards poly-[alpha-(crotonyloxymethyl)acrylate] radical.