Microemulsion polymerization of styrene for obtaining high ratios of polystyrene/surfactant

A modified ternary microemulsion polymerization was successfully used to pr epare nanosized polystyrene (PS) microlatexes with high PS/surfactant weigh t ratios of up to 14:1. Cationic surfactants used were alkyltrimethylammoni um bromides, C(n)TAB, where n is either 12, 14, or 16. A water-soluble init iator was used for the polymerization at room temperature, with moderate st irring. The latexes obtained are bluish-opaque and have been stable now for about 8 months. The process produced rather uniform (D-w/D-n congruent to 1.10) latex particles of about 40 nm having high molar masses of PS ranging from 1.0 to 2.2 x 10(6) g/mol. This was obtained by first generating monom er-starved latex particles in a ternary microemulsion containing only 0.5-1 .0 wt % styrene and 1.0 wt % cationic surfactant. The subsequent supply of styrene monomer to the polymerized microemulsion was delivered either throu gh dropwise addition or via hollow-fiber feeding of monomer. The latter met hod was employed for the first time.