Janus hybrid silica/polymer nanoparticles as effective compatibilizing agents for polystyrene/polyamide-6 melted blends

Silica/polystyrene Janus hybrid nanoparticles (JHNPs) were synthesized at the gram scale via mini-emulsion polymerization technique and then incorporated into polystyrene/polyamide-6 melted blends. Due to their intrinsic amphiphilic properties, the JHNPs migrate to the interface of the PS/PA6 blend during the mixing process and play the role of a compatibilizing agent. First, a significant decrease of the size of the dispersed nodules was observed even at low content of JHNPs, whereas an optimum content of JHNPs corresponding to the saturation of the polystyrene/polyamide-6 (PS/PA6) interface was found in the 3-5 phr range. Secondly, the rheological properties of the blends were also significantly modified. The complex viscosity increased as a function of JHNPs content over the entire frequency range studied. Up to 5 phr of JHNPs, a high increase of the viscosity at low frequencies was observed. This is attributed to the formation of a solid network through the matrix/nodules interface of the nanocomposite. Finally, the Palierne model extended to the field of immiscible polymer blends was used; an important decrease of the effective interfacial tension of the system was observed when JHNPs were added. The asymmetry of these nanoparticles allows the combination of a Pickering effect of a solid particle with a copolymer effect of an amphiphilic structure. The synthesis procedure of JHNPs developed in this work renders these silica/polymer JHNPs interesting as a route for the compatibilization of polymer blends. (C) 2016 Elsevier Ltd. All rights reserved.