The polystyrene living polymer end, which was produced by butyllithium initiated anionic polymerization of styrene in a flow microreactor system was found to be effectively trapped with 1,1-diphenylethylene. The resulting organolithium species could be used as a macro initiator for anionic polymerization of alkyl methacrylates to obtain styrene-alkyl methacrylate diblock copolymers using an integrated flow microreactor system. A high level of control of molecular weight was achieved at easily accessible temperatures such as +24 to -28 degrees C by virtue of the fast mixing, fast heat transfer, and residence time control. Triblock copolymers were also synthesized by sequential introduction of styrene and two different alkyl methacrylates in a similar manner.