The isomerization polymerizations of glycidyl propionate (Ib), octanoate (Ic), and stearate (Id) with methylaluminum bis(2,6-di-tert-butyl-4-methylphenoxide) (3) were investigated. The polymerizations selectively gave poly(2-alkyl-1,3-dioxolane-4,2-diyloxymethylene)s (2), although the polymer yield as well as the polymer molecular weight significantly decreased as the acyl chain of 1 was lengthened. These polymers readily hydrolyzed to glycerin and the corresponding fatty acids under mild conditions. The copolymerizations of glycidyl acetate (1a) with these monomers were also examined. In any combination, the composition of the obtained copolymer was essentially identical with the feed ratio, while both copolymer yield and molecular weight decreased as the feed of la was decreased.