Via in situ intercalative free-radical polymerization, we prepared clay/poly(methyl methacrylate) (PMMA) and clay/polystyrene (PS) nanocomposites from lipophilized smectic clays. The intercalation spacing in the nanocomposites and the degree of dispersion of these composites were investigated with X-ray diffraction and transmission electron microscopy, respectively. Under some conditions, the intercalative nanocomposites exhibited flocculation because of the hydroxylated edge-edge interaction of silicate layers. The nanocomposites had higher storage modulus and higher T-g compared to without clay systems. (C) 2000 Elsevier Science Ltd. All rights reserved.