Some aspects of polymer colloids - III. Preparation and properties of different types of cationic latex particles

Different polymerization pathways concerning nucleation and growth mechanisms of anionic polymer lattices have been reported. However, limited information is available about cationic latices. We described preparation and properties of different types of anionic latex particles in a previous paper [Zimehl et al. (1990) Colloid Polym Sci 268: 924]. This part reports some possibilities to produce cationic latices by emulsion polymerization of styrene. Three types of polystyrene and polystyrene/comonomer lattices are distinguished by the structure of the boundary region which separates the latex particle from the surrounding medium. The mean particle size and the polydispersity index are obtained from quasi-elastic light scattering and transmission electron micrographs. Electron microscopy and the behavior of particles in a centrifugal force field are used as simple tools to gain an insight into particle morphology. The results were compared to the behavior of freeze-dried latex samples during nitrogen gas adsorption at 77 K. In the case of particles with extended boundary regions (core-shell particles or particles with hairy envelopes), film formation can reduce the specific surface area. Removal of soluble oligomers and polymers from the boundary region of these particles often increases the surface area.