The present invention concerns a waterborne copolymer dispersion comprising at least one alkenyl functional dendritic polymer being copolymerized to the polymer backbone of at least one homo or copolymer obtainable by polymerization, such as emulsion polymerization, in an aqueous medium of at least one at least one polymerizable allyl, vinyl, maleic or diene monomer. The dendritic polymer is built up from a dendritic core polymer and at least one alkenyl functional compound bonded to the core polymer. In a further aspect the present invention concerns the use of said copolymer dispersion.