Size-Controlled Polystyrene Microparticles via Thermodynamic Emulsion Polymerization

Controlled emulsion polymerization provides a well-defined and scalable route for synthesizing polystyrene (PS) submicron and nanoparticle dispersions with narrow size distributions. Owing to its ability to achieve high particle uniformity, tunable size control through thermodynamic and kinetic parameters, and compatibility with large-scale production, this technique has been extensively employed in both academic and industrial research. Nevertheless, conventional emulsion polymerization faces inherent limitations in producing micron-sized particles with a high degree of monodispersity, as particle growth is typically confined to the submicron regime. In this study, we systematically investigate the relationship between particle size distribution and key reaction parameters, including polymerization rate and initiator concentration, in emulsion polymerization. By invoking collision theory, we establish a quantitative correlation between particle size, initiator concentration, and reaction temperature, elucidating how these parameters govern nucleation, growth, and aggregation processes. Based on these insights, we develop a robust and systematic synthesis strategy that enables precise control over particle size across the 1–100 μm range by thermodynamically regulating nucleation, condensation, and particle– particle aggregation. Using this approach, we successfully demonstrate the targeted synthesis of monodisperse PS particles with diameters approaching ~100 μm.