We have been working on morphology control in latex particles for many years and have come to learn that achieving desired structures in composite particles is dependent not only upon the emulsion polymerization recipe, but also strongly upon the reaction process conditions. Among those important conditions are the monomer feed rates and the reaction temperature. Figure 1 shows an example of the effect of reaction condition changes upon the latex particle structure, here shown as transmission electron micrographs for styrene/acrylic latex particles.
These particles were formed from the same recipe and reaction temperature but with slow (left), faster (middle) and very fast (right) monomer feed rates. The styrene containing phase is dark in the photos.