The present invention relates to a composition comprising an aqueous dispersion of copolymer particles comprising structural units of vinyl acetate, a cyclic ketene acetal monomer, and a monoethylenically unsaturated acid monomer, or a salt thereof; wherein the cyclic ketene acetal monomer is characterized by following structure: where n and the R groups are as defined herein. The composition of the present invention provides a water-borne dispersion that is substantially free of volatile organic solvents and that provides a readily degradable polymer that is useful, for example, in the manufacture of biodegradable packaging products.