Spontaneous formation of bimodal particle size distributions: A novel one-step strategy for obtaining high solid content, low viscosity poly(vinyl acetate- co -ethylene) latexes

Abstract

Abstract A novel one-step semi-batch method was developed as a means of synthesizing vinyl acetate- co -ethylene (VAE) latexes with bimodal particle size distributions (PSDs). This technique allows high solid content while maintaining extremely low viscosity. In contrast to previous methods, the formation of a bimodal PSD based on the limited auto-aggregation of particles was found to occur spontaneously. The effects of the reaction temperature, initiator concentration, surfactant concentration, sodium dodecyl sulfate (SDS)/nonionic surfactant ratio and reaction time on the PSD and solid content of the latex were all investigated. A stable VAE latex consisting of 78.4 vol% large particles and 21.6 vol% small particles with a large-to-small particle diameter ratio of 4.51 was readily synthesized using this approach. The viscosity of one such latex with a 71.83 wt% solid content was below 300 mPa s at a constant shear rate of 20 s −1 . This synthesis method was also demonstrated to be highly reproducible.