Emulsion Polymerization of Styrene to Polystyrene Nanoparticles with Self-Emulsifying Nanodroplets as Nucleus.

The mechanism of the emulsion polymerization of styrene to polystyrene nanoparticles (PSNPs) remains a subject of debate. Herein, a series of reaction parameters with different surfactant concentrations, monomer contents, temperatures, and equilibration times were investigated to understand the formation mechanism of PSNPs, which demonstrate a correlation between the properties of PSNPs and the mesostructure of the premix. Cooling the model systems with self-emulsifying nanodroplets (SENDs) in the early reaction stages resulted in the hollow polystyrene spheres (H-PSSs), ruptured PSNPs, and dandelion-like PSNPs, further indicating that the oil nanodroplets are the key sites for the formation of PSNPs.

Fabrication of tetraethyl orthosilicate/ethanol-water surfactant-free microemulsions and their applications in self-templating synthesis of monodispersed silica colloidal spheres.

Surfactant-free microemulsions (SFMEs) composed of tetraethyl orthosilicate (TEOS), ethanol, and water have been successfully fabricated by visual titration and electrical conductivity methods. Three types of SFMEs, water in TEOS (W/O), bicontinuous (BC) and TEOS in water (O/W), were identified by dynamic light scattering and transmission electron microscopy with negative-staining methods. We demonstrated that there are significant differences in the properties of silica products synthesized with different types of SFMEs, and monodispersed silica colloidal spheres (MSCSs) can only be synthesized in the O/W type SFMEs.