Mesostructurally ordered inorganic-organic hybrid composite materials were successfully synthesized by utilizing a low-molecular-weight amphiphilic polyethylene-block-poly(ethylene oxide) (PE-PEO) diblock copolymer as the directing agent. The hybrid composites were formed via the sol-gel reaction of inorganic precursor tetraethoxysi lane (TEOS) in an acidic ethanol/water solution with various amounts of PE-PEO. In these composite materials, the hydrophobic PE block of the PE-PEO copolymer forms separate microphase on the nanoscales within the rigid matrix of silica network. The crystallization of the PE block is strictly restricted within the microphase by the rigid silica matrix and takes place through homogeneous nucleation under the nanoscale confinement environment. (c) 2007 Elsevier Ltd. All rights reserved.