Design and Controlled Synthesis of Sub‐50 nm Polystyrene Seed Latexes for Emulsion Polymerization

This study presents a comprehensive investigation into the synthesis of sub‐50 nm polystyrene seed latexes via emulsion polymerization, with a specific focus on the influence of both material (formulation) and processing parameters on particle size, distribution, and stability. Through systematic experimentation, we optimized the use of a sulfosuccinate‐based surfactant system ( Sodium dicycloalkyl sulfosuccinate ), both alone and in dual‐surfactant configurations with a disulfonate co‐surfactant ( Alkyl diphenyl oxide disulfonate sodium salt ), to enhance micelle formation and colloidal stability. Key variables including surfactant concentration/initiator levels (material/formulation parameters) and reaction time/temperature (processing parameters) were fine‐tuned to achieve precise control over particle nucleation and growth. The resulting polystyrene (PS) seed latexes exhibited uniform particle sizes as small as 25 nm, narrow polydispersity indices (~2.6%), and excellent electrostatic stability (zeta potential ~−44 mV). Reaction temperature showed minimal influence, indicating a robust process suitable for industrial scale‐up. The protocol developed herein enables reproducible synthesis of nanoscale, monodisperse PS seeds, providing a foundational framework for advanced emulsion polymerization systems, especially in the production of styrene‐butadiene rubber latexes.