Synthesis of High Solids Content Low Surfactant/Polymer Ratio Nanolatexes

A new two-stage strategy for the synthesis ofhigh-solids-content low-surfactant/polymer ratio nanolatexeswas developed. In the first stage, the knowledge-based strategyis used to obtain 18 wt % nanolatexes with the maximumnumber of particles and using a fraction of the surfactant. Inthe second stage, the rest of the surfactant is employed tostabilize these particles while they are growing to reach thetarget solids content. The final particle size results from theinterplay between limited particle coagulation and secondaryhomogeneous nucleation during the second stage. Smallerparticle sizes were obtained for surfactants able to desorb fromthe existing particles and diffuse quickly to the newly formed particles. Waterborne nanoparticles as small as 32 nm in diameterwere obtained with 36 wt % solids content and solids content/(surfactant/polymer) ratio higher than 26. This represents asubstantial improvement with respect to the best results reported in the literature (dp = 32 nm; 23 wt % solids, and solidscontent/(surfactant/polymer) = 21).