Self-assembly of Janus Magnetic colloids with radially shifted dipole

Abstract

The self-assembly Janus Magnetic colloids with radially shifted dipole are stud- ied using Brownian dynamics simulations, by is using a quasi-two-dimensional sys- tem. The properties and behavior of the process of particle-particle and cluster- cluster aggregation are quantified for several dipolar shifts (s) and examined under different dipolar coupling constant parameter (λ). Properties such as the mean clus- ter size, orientational ordering, and nucleation and growth are examined dynami- cally. Seven different clusters regions have been found, these regions are dependent on the relation between λ and s. Furthermore, five of this seven structures are formed through three different types of aggregations, for high λ: First, the Lin- ear Aggregation (small s), with building block doublet (head to tail aggregation), Single-Chain and Loop-Like region. Second, the Bidirectional Aggregation (inter- medium s), with building blocks triplet (triangular arrangement, acute angles) and quartets (square arrangement), the particles tend to form a cluster with bidirec- tional growing forming compact clusters, Island Region. Third, the Double Chain Aggregation (high s, s ≥ 0.65), with building blocks triplet (triangular arrangement, obtuse angles) and quartets (parallelogram arrangement), it′s characterized by ori- ented growth, the cluster form a double-chain structure with the magnetic surface at the center, Worm-Like and Antiparallel-Double-Chain region. The other two cluster regions occurs for low λ and are shorts cluster characterized by an inability to grow: Short-Life-Cluster (low and intermedium s) and Triplets (high s, s ≥ 0.65) region.