Emulsion polymerization of styrene using a new series of rigid rod-like cationic surfactants

A series of pyridinium salts (PCX) N-substituted with an ω-(4′-methoxy-4-biphenylyloxy)alkyl group has been synthesized and used as surfactants in the emulsion polymerization of styrene. These molecules have an alkyl chain with an even number (X = 6, 8, 10, or 12) of methylene groups and bromine as counterion. For these molecules a typical behavior of colloidal electrolytes has been observed by conductivity measurements on water solutions and the critical micelle concentrations (CMC) determined by this technique are 2.14, 1.47, 0.214, and 0.0097 mmol for PC6, PC8, PC10, and PC12, respectively. Latices prepared with three components (water/styrene/PCX) were fairly stable showing in all experiments a monodisperse particle size distribution (1.01 to 1.1) with particle diameters from 70 to 160 nm. These results are compared with those obtained using dodecylpyridinium bromide (DPB) as the surfactant.