Star polymers made from macromonomers made by cobalt chain transfer process

摘要

A polymer dispersion of a star polymer dispersed in an organic liquid; wherein the star polymer has a crosslinked core having attached thereto at least three macrononomer arms; where (1) the core is formed of monomers having at least two ethylenically unsaturated double bonds which are crosslinked with each other and the core has at least 3 free radical polymerizable sites each of which are reacted with the macromonomer; and (2) the macromonomer that forms the arms of the star polymer is formed of ethylenically unsaturated monomers that have been polymerized by free radical polymerization in the presence of a free radical polymerization initiator and a catalytic chain transfer agent containing CO+2 to provide the macromonomer with a terminal ethylenically unsaturated group that is polymerized with the free radical polymerizable site on the core to form the star polymer. The process for making the star polymer and coating compositions that utilize the star polymer are also part of this invention.