Role of bulky α-substituent in free-radical polymerization and copolymerization of methyl α-(alkoxymethyl)acrylates

Methyl α-(alkoxymethyl)acrylates were prepared from methyl α-(bromomethyl)acrylate in 80–90% yield. The monomers homopolymerize fast to yield low-molecular-weight polymers. The monomers bearing a linear alkoxymethyl group except for the ethoxymethyl group are characterized by a relatively low ceiling temperature. The rate constants for propagation k_p and termination k_t of methyl α-(butoxymethyl)acrylate were evaluated to be k_p = 298 dm³ · mol^?1 · s^?1 and k_t = 8 · 10⁶ dm³ · mol^?1 · s^?1 at 60°C, respectively. The α-(alkoxymethyl)acrylates are more reactive than methyl methacrylate toward polystyrene radical, except for the α-(dodecyloxymethyl)acrylate which is slightly less reactive, indicating that an increase in the reactivity by the electron-withdrawing character of the alkoxy group prevails over the steric hindrance against addition of the polymer radical, except for the large dodecyloxymethyl group.