Emulsifier-free emulsion copolymerization of styrene and butylacrylate:: particle size control with synthesis parameters

This paper presents the synthesis of film-forming particles with controlled diameters. The copolymerization of styrene and butylacrylate is realized by emulsion synthesis in the presence of potassium sulfopropylmethacrylate (SPM), an ionogenic monomer and sodium bicarbonate. The initiator, ammonium persulfate, and the SPM ensure the stabilization of particles. After the particles are washed, their diameters are measured by Dynamic Light Scattering (DLS) with a Zetasizer 3 (Malvern). The particle diameters are controlled by SPM concentration and the ionic strength of the medium. An increase of ionic strength, at constant [SPM], increases diameters, though an increase of [SPM], at constant ionic strength, decreases diameters. The experimental results are interpreted by two different modelizations, either by log-log equations like in the literature, or by semi-log and exponential equations. The latter ones give better modelization.