In this work, we report how micellar structures obtained by the self-assembly in heptane of polyisoprene-block-poly(methyl methacrylate) (PI-b-PMMA) and polyisoprene-block-poly(ethylene oxide) (PI-b-PEO) can be effectively used as organic supports for ethylene polymerization catalyzed by metallocene and post-metallocene catalysts. The self-assembly in heptane of these block copolymers was demonstrated by means of dynamic light scattering and the influence of methylaluminoxane (MAO) on this self-assembly was analyzed. The so-formed assemblies, composed of either PMMA or PEO cores and PI corona, were used as organic supports for metallocene or post-metallocene catalysts with methylaluminoxane (MAO) as an activator, to produce micrometric polyethylene beads