The synthesis of fluorinated latex colloids by emulsion polymerization in water has recently been reported. The motivation for this work was that fluorinated latex has an unusually low refractive index of 1.37, compared to the typical value of 1.5 for commonly used colloidal particles such as silica, polystyrene (PS), and poly(methyl methacrylate) (PMMA). Aqueous dispersions of silica or latex are generally turbid because of the large difference between the refractive index of the particles and that of water (1.33). Instead, fluorinated particles can be relatively easily optically matched to give transparent dispersions. This allows the study of the structure and dynamics of model colloidal sphere dispersions by light scattering and microscopy even at high volume fractions. It is well-known that small, monodisperse particles such as PS and PMMA can be synthesized using a microemulsion (see, for instance, refs 2 and 3). In a microemulsion, the size of micelles can be controlled by varying the ratio of surfactant/cosurfactant, and with respect to a classical emulsion polymerization this allows a fine control on the final particle size and high reproducibility. Moreover, because of the transparency of microemulsion systems, UV light provides an alternative and interesting method to initiate polymerization.

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