Synthesis of High Solids Content Low Surfactant/Polymer Ratio Nanolatexes

A new two-stage strategy for the synthesis of high-solids-content low-surfactant/polymer ratio nanolatexes was developed. In the first stage, the knowledge-based strategy is used to obtain 18 wt % nanolatexes with the maximum number of particles and using a fraction of the surfactant. In the second stage, the rest of the surfactant is employed to stabilize these particles while they are growing to reach the target solids content. The final particle size results from the interplay between limited particle coagulation and secondary homogeneous nucleation during the second stage. Smaller particle sizes were obtained for surfactants able to desorb from the existing particles and diffuse quickly to the newly formed particles. Waterborne nanoparticles as small as 32 nm in diameter were obtained with 36 wt % solids content and solids content/(surfactant/polymer) ratio higher than 26. This represents a substantial improvement with respect to the best results reported in the literature (dp = 32 nm; 23 wt % solids, and solids content/(surfactant/polymer) = 21).