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Monodisperse suspensions of poly(methy1 methacrylate) in n-tetradecane were prepared with mean particle diameters ranging from 0-4 to 4-5 p. The dispersions were sterically stabilized with an amphipathic polymer in which the soluble stabilizing component was the hexamer of 12-hydroxystearic acid. Preliminary rheological and related data indicate the presence of a stabilizing barrier on the particles which is more than sufficient to overcome the interparticle Van der Waals attractions.Colloidal dispersions in non-aqueous media, which are stabilized by the steric barriers formed by molecules adsorbed on the particles (entropic stabilization) have not been extensively investigated. Studies have been published of dispersions of carbon black 1 and of inorganic particles in hydrocarbon media 2 and of water in oil emulsions.3 Whilst Koelmans and Overbeek 2 concluded from theoretical considerations that only small particles, in which the stabilizer length was comparable with the particle size, could be stabilized by steric hindrance, the later work on water-in-oil emulsions suggested that the Van der Waals attraction in non-aqueous media was much smaller than predicted.Osmond and co-workers have developed methods for the preparation of colloidal dispersions of poly(methy1 methacrylate) in aliphatic hydrocarbons.4? 5 These dispersions are sterically stabilized by amphipathic polymers, one component of which, usually poly(methy1 methacrylate), is insoluble in the medium, whilst the other component is a polymer soluble in the hydrocarbon medium. Using these stabilizers it is possible to prepare concentrated monodisperse suspensions of polymer in pure hydrocarbons. In this paper we describe such dispersions and give a preliminary account of their rheological and related properties.

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