Graft copolymers with polystyrene backbone and poly (methyl methacrylate) branchs were synthesized via three steps: (1) free-radical copolymerization of styrene and desired amount of 2-vinylfluorene

(2) metallation of the fluorene units in the copolymers

(3) anionic graft polymerization of MMA initiated by the carbanion sites at the fluorene units. GPC measurements have proved that almost no homopolymers remain in the products. The molecular weights of the copolymers

backbones and branchs and the number of the branchs on each backbone have been determined directly or calculated.