Viscoelastic properties of polystyrene/polyamide-6 blend compatibilized with silica/polystyrene Janus hybrid nanoparticles

The greatest challenge in the field of multiphase polymer blend research is the compatibility of the phases, which is responsible for the overall microstructure. The control of the interfacial interactions between the components is therefore a necessity. Here, we investigate the compatibilization in a polystyrene/polyamide-6 (PS/PA6) blend. Silica/polystyrene Janus hybrid nanoparticles (JHNPs) were synthesized and used as compatibilizing agents in PS/PA6 blends. Four levels of incorporation were tested (1.5, 3, 5, and 10 phr) in a PS/PA6 (80/20 wt. %) blend. Due to their intrinsic amphiphilic properties, the JHNPs migrate to the interface of the PS/PA6 blend. We demonstrate that silica/polystyrene JHNPs act as compatibilizing agents in PS/PA6 blends. These nanoparticles allow the combination of a "Pickering effect" of a solid particle with a "copolymer effect." Microscopic analysis confirms the emulsifying ability of these asymmetric nanoparticles. Rheological measurements show an increase in the viscosity with the level of particle incorporation. Relaxation spectra reveal additional peaks (related to slower process) as JHNPs are added into the pristine blend. These peak occurrences can be related, via modeling, to interfacial tension. The compatibilizing effect of the JHNPs is confirmed by a decrease in interfacial tension up to 5 phr of particles.