216: Synthesis of polystyrene nanoparticles with controlled size via emulsion polymerization

The synthesis of monodisperse polystyrene nanoparticles has attracted significant attention due to their extensive applications in diverse fields[1]. The emulsion polymerization process is mainly used to produce polymer nanoparticles. Despite the numerous studies on emulsion polymerization, the focus on particle size control has been limited. Moreover, most studies do not fully disclose hydrodynamic conditions, making it difficult to compare results among different research groups.

In this study, it was established that reactor geometry and stirring rate are critical factors for ensuring reproducibility in experimental results and achieving a narrow particle size distribution. The findings indicate that the diameter of the particles and the coefficient of variation are dependent on the stirring speed (Fig. 1a). The lowest value of the coefficient of variation was observed at a stirring speed of 800 rpm (Fig. 2b).

Fig.1. (a) Particle diameter and C_v vs. stirring rate dependence; (b) SEM photograph of polystyrene particles obtained at a stirring speed of 800 rpm.

             In turn, the particle size can be effectively controlled by changing the concentrations of the monomer and emulsifier. Accordingly, polystyrene particles with diameters ranging from 110 to 590 nm were obtained (C_v<3%). It is noteworthy that changes in the initiator concentration (2.5-20 mM) exhibited a negligible influence on the particle diameter.

In summary, simple and reproducible methods have been developed to obtain monodisperse polystyrene particles with diameters ranging from 110 to 590 nm (C_v<3%).

Acknowledgment: this work was carried out within the framework of the State programme for scientific research of Belarus «Chemical processes, reagents and technologies, bioregulators and bioorganic chemistry» (assignment 2.1.01.03, state registration №. 20210512).