Title
Self-assembly of magnetic colloids with radially shifted dipoles
Date Issued
14 March 2020
Access level
metadata only access
Resource Type
journal article
Author(s)
Victoria-Camacho J.A.
Kretzschmar I.
Córdova-Figueroa U.M.
University of Puerto Rico-Mayaguëz
Publisher(s)
Royal Society of Chemistry
Abstract
Anisotropic potentials in Janus colloids provide additional freedom to control particle aggregation into structures of different sizes and morphologies. In this work, we perform Brownian dynamics simulations of a dilute suspension of magnetic spherical Janus colloids with their magnetic dipole moments shifted radially towards the surface of the particle in order to gain valuable microstructural insight. Properties such as the mean cluster size, orientational ordering, and nucleation and growth are examined dynamically. Differences in the structure of clusters and in the aggregation process are observed depending on the dipolar shift (s)-the ratio between the displacement of the dipole and the particle radius- A nd the dipolar coupling constant (λ)-the ratio between the magnetic dipole-dipole and Brownian forces. Using these two dimensionless quantities, a structural "phase" diagram is constructed. Each phase corresponds to unique nucleation and growth behavior and orientational ordering of dipoles inside clusters. At small λ, the particles aggregate and disaggregate resulting in short-lived clusters at small s, while at high s the particles aggregate in permanent triplets (long-lived clusters). At high λ, the critical nuclei formed during the nucleation process are triplets and quadruplets with unique orientational ordering. These small clusters then serve as building blocks to form larger structures, such as single-chain, loop-like, island-like, worm-like, and antiparallel-double-chain clusters. This study shows that dipolar shifts in colloids can serve as a control parameter in applications where unique size, morphology, and aggregation kinetics of clusters are required.
Start page
2460
End page
2472
Volume
16
Issue
10
Language
English
OCDE Knowledge area
Nano-tecnología Nano-tecnología
Scopus EID
2-s2.0-85081787063
PubMed ID
Source
Soft Matter
ISSN of the container
1744683X
DOI of the container
10.1039/c9sm02020a
Sponsor(s)
This project was supported by the National Science Foundation under Awards NSF-CBET 1705656 and NSF-HDR CREST IDEALS 1547830.
Sources of information: Directorio de Producción Científica Scopus