Transportation of Janus Nanoparticles in Confined Nanochannels: A Molecular Dynamics Simulations

Abstract

Janus nanoparticles (NP) have drawn great attention due to their unique surface of dual characters. In this study, transportation of Janus NPs contained two-phase fluids in an ultra-confined channel was studied by molecular dynamics (MD) simulations. The results indicated that the fluid displacement was hindered by Janus NPs, to an extent largely dependent on the concentration of NPs self-assembled at fluids interface. Different from NPs with uniform surface properties, the determining migration states for Janus NPs to influence displacement process were self-assembled at fluids interface and aggregated at three-phase contact region, which modified the interfacial tension and three-phase contact angle. Such key migration states were validated by the potential of mean force of Janus NPs transporting from water to oil phase. The capillary pressure calculated by local pressure distribution was found to be the key factor driving the displacement process of nanofluids with Janus NPs. Our findings revealed the microscopic transportation mechanism for fluids with Janus NPs into porous materials, which had significant implication to application fields such as enhanced oil recovery, drug delivery, inkjet printing, etc.