A one-step method was used to prepare stable aqueous nanocomposite dispersions based on cellulose whiskers extracted from the rachis of the date palm tree and a poly(styrene-co-2-ethyl hexylacrylate) copolymer via mini-emulsion polymerization A reactive Mane, i e, methacryloxypropyl triethoxysilane was added to stabilize the dispersion and favor the anchoring of the whiskers on polymer particles Dynamic light scattering was used to study the effect of the Mane and whiskers contents on the average particle size of the polymer Nanocomposites materials were prepared from these dispersions using a casting/evaporation method The effect of the slime and whiskers contents on the thermal and mechanical properties were studied using differential scanning calorimetry and dynamic mechanical analysis POLYM ENG SCI, 51 62-70, 2011 (C) 2010 Society of Plastics Engineers