Supramolecular complexes of alkali metals were used as catalysts in the polymerization of isoprene via a two-electron-transfer mechanism. The obtained polyisoprene, having a living end group, was subsequently used to initiate methyl methacrylate polymerization in tetrahydrofuran. Polyisoprene-poly(methyl methaerylate) block copolymers were obtained, and their structure was established with H-1 NMR, gel permeation chromatography, differential scanning calorimetry, and experiments of selective extraction. (c) 2005 Wiley Periodicals, Inc.