Microemulsion polymerization in the water, aerosol-OT, tetrahydrofurfuryl methacrylate system

Part of the phase diagram at low (<10%) oil content and 25°C has been mapped in the water, Aerosol-OT (AOT), tetrahydrofurfuryl methacrylate (THFM) ternary system. Sodium persulfate/sodium metabisulfite was used as a redox initiator to induce polymerization in this microemulsion system at 7.8% (w/w) THFM and 4.4% AOT. Conversions in excess of 90% were obtained. The parent microemulsion droplets have diameters on the order of 5 nm. The resulting latexes have average particle diameters of 37–39 nm. The latex particles are cross-linked as a result of radical induced opening of the tetrahydrofurfuryl ring, and exhibit nearly the same density (1.216 g/cm3) and glass transition temperature (67°C) as material (1.222 g/cm3; 62°C) produced by solution polymerization. This three-component microemulsion, and the corresponding latexes, have been imaged directly by cryo-electron microscopy. The first reports of three-component polymerized (oil in water) microemulsions, stabilized by cationic surfactants, were made by Murtagh, Ferrick, and Thomas [ACS Polymer Preprints1987, 28, 441] and more recently by Perez-Luna, Puig, Castano, Rodriguez, Murthy, and Kaler [Langmuir1990, 6, 1040]. this report appears to be the first such polymerization in a three-component system stabilized with an anionic surfactant. These latexes are cross-linked beads, and are the first such examples to be prepared by microemulsion polymerization.