Microemulsion polymerization of styrene using a polymerizable nonionic surfactant and a cationic surfactant

High polymer/surfactant weight ratios (up to about 15:1) of polystyrene mic rolatexes have been successfully produced by microemulsion polymerization u sing a small amount of polymerizable surfactant, omega -methoxypoly(ethylen e oxide)(40) undecyl alpha -methacrylate macromonomer (PEO-R-MA-40), and ce tyltrimethylammonium bromide (CTAB). After generating "seeding particles" i n a ternary microemulsion containing only 0.2 wt% CTAB and 0.1 wt% styrene, the additional styrene containing less than I wt% PEO-R-MA-40 was added dr opwise to the polymerized microemulsion for a period of about 4 h at room t emperature. PEO-R-MA-40 copolymerized readily with styrene. The stable micr olatexes were bluish-transparent at a lower polymer content and became blui sh-opaque at a higher polymer content. Nearly monodisperse latex particles with diameters ranging from 50 to 80 nm and their molar masses ranging from 0.6 to 1.6 x 10(6) g/mol could be obtained by varying the polymerization c onditions. The dependence of the number of particles per milliliter of micr olatex, the latex particle size and the copolymer molar mass on the polymer ization time is discussed in conjunction with the effect of the macromonome r concentration.