| Polymerization of monomers in microemulsions results in latexes with smaller particle diameters (;Two three-component microemulsions are investigated. The first contains tetrahydrofurfuryl methacrylate, Aerosol OT (AOT), and water. The resulting monodisperse microlatex have particles with mean diameters from 32 to 46 nm and polymer molecular weights of order 10;The second microemulsion studied contains styrene, dodecyltrimethyl-ammonium bromide, and water and is examined as a function of potassium bromide (KBr) concentration. The resulting microlatex is stable, but as the KBr concentration increases, the polymerization rate, radius, and molecular weight decrease. Both particle radius and molecular weight show only limited growth as styrene conversion increases, suggesting that latex particles are continuously nucleated. SANS measurements of parent and undiluted polymerized microemulsions indicate that a unimodal population of swollen micelles evolves into a bimodal population of empty micelles coexisting with large polymer particles. Structural details of the parent and polymerized microemulsion as determined by SANS and QLS are used to assess nucleation mechanisms previously proposed for emulsion polymerization. |
