Vinylbenzyl-terminated polystyrene (PS) and polyisoprene (PI) macromonomers were synthesized by the coupling reaction of corresponding living anions with p-chloromethylstyrene. Free-radical copolymerizations of binary PS and PI macromonomers were carried out in benzene, varying the molecular weight of macromonomers. The reactivity ratios of these systems were close to an azeotropic copolymerization, in the case of the same degree of polymerization of binary macromonomers.