Polyethylene-block-poly(methyl methacrylate) (PE-b-PMMA) was successfully synthesized through the combination of metallocene catalysis with living radical polymerization. Terminally hydroxylated polyethylene, prepared by ethylene/allyl alcohol copolymerization with a specific zirconium metallocene/methylaluminoxane/triethylaluminum catalyst system, was treated with 2-bromoisobutyryl bromide to produce terminally esterified polyethylene (PE-Br). With the resulting PE-Br as an initiator for transition-metal-mediated living radical polymerization, methyl methacrylate polymerization was subsequently performed with CuBr or RuCl2(PPh3)(3) as a catalyst. Then, PE-b-PMMA block copolymers of different poly(methyl methacrylate) (PMMA) contents were prepared. Transmission electron microscopy of the obtained block copolymers revealed unique morphological features that depended on the content of the PMMA segment. The block copolymer possessing 75 wt % PMMA contained 50-100-nm spherical polyethylene lamellae uniformly dispersed in the PMMA matrix. Moreover, the PE-b-PMMA block copolymers effectively compatibilized. homopolyethylene and homo-PMMA at a nanometer level. (C) 2003 Wiley Periodicals, Inc.