Dynamics of nucleation and growth mechanism in the presence of nanoparticles or block copolymers: polystyrene/poly(vinyl methyl ether)

This study aimed at controlling the phase separation kinetics in the metastable region of polystyrene/poly(vinyl methyl ether) (PS/PVME) blend by adding a block copolymer or hydrophilic and hydrophobic nanoparticles as the compatibilizer. We studied the effects of compatibilizer localization and volume fraction on the dynamics of nucleation and growth (NG) mechanism. For this purpose, time sweep experiments were performed using rheological analysis and phase contrast optical microscopy. Based on the results, hydrophilic nanosilica with preferential affinity to the PVME-rich matrix phase slowed down efficiently the phase separation and beyond a critical volume fraction, pinned the domain growth. The block copolymer, self-assembling along the interface, caused a considerable decrease in phase separation kinetics as well. However, its efficiency was lower than the hydrophilic nanosilica and in the range of the applied volume fractions, no pinning behavior was observed. The hydrophobic nanosilica which preferentially wetted the PS-rich droplets had the minimal effect on phase separation. It was observed that adding nanoparticles or block copolymer could change the dynamical scaling of phase separation.