Self-assembly And Dynamics Of Active Colloidal Cells

Active matters is a kind of material that can convert the energy stored in itself or environment into its own mechanical movement.In recent years,various artificial active matters have been designed and manufactured in the laboratory,which has greatly promoted the study of the dynamic behavior of the active matters system.We are inspired by the structure and behavior of cells and study a simple combination.It is formed by vesicle encapsulating the active colloidal particles,which is known as the active colloidal cell.The vesicle can move autonomously and deform like a cell.Our study focused on the group selfassembly structure and dynamic behavior of the active colloidal cells.We compared two types of active colloidal cells composed of rigid vesicles and flexible vesicles.Although the statistical dynamics of their monomers are basically consistent,they show a significant difference in assembly behavior.The collective behavior of rigid active colloidal cells is similar to active colloidal particles.In low density,they can form distinct clusters and gas and solid phase separation occurs in the system in medium density.This phenomenon is known as motility-induced phase separation.However,we found that the deformation ability of the flexible active colloidal cells resulted in the obvious decrease of their ability to form cluster,and the morphology of the cluster was different.The cluster of active colloidal particles or rigid active colloidal cells is a cluster of independent and tightly packed clusters similar to crystals in structure.However,the cluster of flexible active colloidal cells is in a network,and its accumulation is irregular due to individual deformation.In the high density,the motility-induced phase separation of the flexible active colloidal cells is not obvious.The cluster of rigid active colloidal cells in dynamics is stable,and there is no individual flow inside.However,the flexible active colloidal cells can be deformed,and the individual flows in the cluster are very strong.Therefore,even in the formation of a large number of clusters,the mobility of flexible active colloidal cells is still very strong.By comparing the self-assembly phase behavior of rigid and flexible active colloidal cells,this paper reveals the uniqueness of the behavior of the deformable active matter.It provides reference for understanding,designing and applying the non-equilibrium collective motion of soft active matters.