In situ bulk polymerization of polymethylmethacrylate (PMMA)-clay nanocomposites was initiated with a benzoyl peroxide/amine redox couple at room temperature. This was accomplished with a newly synthesized cationic molecule-containing an aliphatic chain and an aromatic tertiary amine-that was ion exchanged onto the clay surface in order to control the rate of intragallery polymerization relative to that of extragallery polymerization. The rate and location of initiation significantly affected the degree of dispersion of the silicate layers. Accelerating intragallery polymerization of clay with low cation exchange capacity was found to produce the maximum interlayer distance as evident from transmission electron microscope images. (c) 2005 Elsevier Ltd. All rights reserved.