Study of particle growth by seeded emulsion polymerization accompanied by electrostatic coagulation

A seeded emulsion polymerization was conducted in order to prepare an emulsion composed of large-sized particles, which was carried out in parallel with the controlled coagulation process induced by the formation of secondary polymers having an opposite charge to the surface charge of the seed particles. As the first part of this study, effects of agitation rate during the seed polymerization, size of the seed polymer particles and controlled pH of the reaction mixture were investigated. The lower agitation rates yielded a stable latex composed of large-sized grown particles, whereas the higher, intensive agitation rates induced undesirable coagulation between the larger particles, forcing them to separate from the latex. It was revealed that the smaller seed particles performed a well-controlled coagulation and yielded a larger particle size. The lower pH (8.0–8.5) reduced the solid content in the latex due to an uncontrollable formation of coagulums. At the higher pH (9.5–10.0), the controlled coagulation was not as effective as those obtained at the intermediate pH (8.75–9.0).