The effect of Janus nanospheres on the phase separation of immiscible polymer blends via dissipative particle dynamics simulations

Abstract

Using dissipative particle dynamics simulations, we have studied the effect of Janus nanospheres on the phase separation dynamics of polymer blends. We find that Janus nanospheres significantly impede domain growth and at a later stage the average domain size approaches saturation and the growth exponent n decays to near-zero. Additionally, compared with homogeneous nanospheres, the phase separation dynamics of ternary systems containing Janus nanospheres is slower and the average size of domains is smaller at later stages of the phase separation process. This mainly arises from the inherent equatorial adsorption and low desorption probability of Janus nanospheres at interfaces, which can greatly reduce the interfacial tension and hence the driving force towards macrophase separation. In particular, such a difference in the retardation effect becomes more pronounced for the systems containing small sized nanospheres with the preferential particle-matrix interaction. Furthermore, in the later-stage of the phase separation process there exists a dynamical self-similarity in the ternary systems that undergo microphase separation and the domain growth follows a crossover scaling form. Similarly, ternary systems containing Janus nanospheres are closer to saturation and the extracted crossover scaling exponent is closer to 1 than the counterpart ternary systems containing homogeneous nanospheres. Therefore, the Janus nanospheres can be used as a more effective emulsifying or stabilizing agent than homogeneous nanospheres for immiscible polymer blends.