The radical homopolymerization of captodatively substituted methyl alpha-acetoxyacrylate (MAA) is studied by comparing it with that of the alpha-trifluoroacetoxy, the alpha-butyryloxy, and the ethyl ester analogs at 40 degrees C. The yield of the polymer is much influenced by the acyloxy substituents, and the polymer molecular weight increases with conversion in bulk MAA and ethyl ester polymerizations in contrast to other polymerizations, Dilution of the MAA polymerization system, however, results in no increase in the polymer molecular weight during the polymerization. Some polymer-polymer interactions between captive and dative moieties in MAA polymer are discussed on the basis of the measurement of the viscosity of the polymerization system and the polymer solution.