Microfluidic-supported emulsion polymerization: molecular weight and concentration of surface-capping agents impact the formation of anisotropic polyvinylmethacrylate particles

Surface-capping agents—for example, amphiphilic surfactant molecules, water-soluble polymers, or polyelectrolytes—play a critical role during polymerization reactions for both the formation and stability of colloidal polymer particles. Here, we investigated the effect of the molecular weight and concentration of polymeric surface-capping agents on the assembling of polyvinyl methacrylate (PVMA) colloidal nanoparticles (NPs) via microfluidic-supported emulsion polymerization. Specifically, the impacts of the molecular weight and concentration of polyvinylpyrrolidone (PVP, molecular weights of 10 000, 40 000, 360 000, and 1 300 000 MW, concentrations of 0.05, 0.5, 1, 2.5, 5, and 10 mM, repeating unit concentration) and poly(sodium styrene sulfonate) (PSSS, molecular weights of 70 000 and 200 000 MW, concentrations of 0.1, 1, 2.5, 5, 10, and 20 mM, repeating unit concentration) on the formation of PVMA NPs were investigated. Depending on the molecular weight and concentration of surface-capping agents, we obtained finely textured assembled, spherical, flower-shaped, fluffy, and elongated spherical PVMA NPs with sizes ranging from 70 to 500 nm. With our microfluidic-supported synthesis of PVMA NPs, we contributed to a basic understanding of how the molecular weight and concentration of surface-capping agents impact the formation of polymer NPs.