Brownian Dynamics Simulation Of Self-assembly Of Janus Ellipsoids

In mesoscopic and macroscopic scale,the condensed structure of matter is closely related to the specificity of the mesoscopic building block.The interaction between anisotropic particles depends not only on the size and spatial separation,but also on the specific morphology and surface distribution characteristics of the particles.There are three classes of complex mesoscopic particles: Janus particles and patchy particles;polyhedral particles and special shape particles;irregular shape colloidal particles formed by biological macromolecules(proteins).Janus ellipsoid as a mesoscale building block can aggregate into variously micelle-like structures in solution that have potential applications in many fields such as novel surfactant,photonic crystal,drug delivery and biochemical sensor.In this work,we present a novel nonspherical-particle model to investigate the self-assembly of Janus ellipsoid,which quantitatively reflects interaction dependence on particle shape.The phase diagrams of Janus ellipsoids depending on aspect ratio and component ratio are achieved and various aggregates are observed such as sandwich-type structure,columnar aggregate,vesicle,liquid crystal,random aggregation structure,spherical micelle and wormlike micelle.The specific heat capacity curves and temperature evolutions illustrate the formation processes of assembled superstructures detailedly.We analyze the potential energy surfaces(PESs)of interaction between two Janus ellipsoids and the minimum energy paths(MEPs)between saddle points on the PESs.It is found that the number of metastable conformation and the activation energy along MEPs rely not only on ellipsoidal shape but also on component ratio.This work provides rich and valuable information for deep understanding the self-assembly mechanism of Janus ellipsoids and design of new mesoscale building blocks.Through the simulation of self-assembly of Janus ellipsoid,the effect of the particle morphology and interaction on the thermodynamic and kinetic properties in the process of aggregation is deeply understood.And it provides guidance for further research on the assembly of polyhedral particles and biological macromolecules.