title: Self-assembly of colloidal particles into strings in a homogeneous external electric or magnetic field.
abstract: Colloidal particles with a dielectric constant (magnetic susceptibility) mismatch with the surrounding solvent acquire a dipole moment in a homogeneous external electric (magnetic) field. The resulting dipolar interactions can lead to aggregation of the particles into string-like clusters. Recently, several methods have been developed to make these structures permanent. However, especially when multiple particle sizes and/or more complex shapes than single spheres are used, the parameter space for these experiments is enormous. We therefore use Monte Carlo simulations to investigate the structure of the self-assembled string-like aggregates in binary mixtures of dipolar hard and charged spheres, as well as dipolar hard asymmetric dumbbells. Binary mixtures of spheres aggregate in different types of clusters depending on the size ratio of the spheres. For highly asymmetric systems, the small spheres form ring-like and flame-like clusters around strings of large spheres, while for size ratios closer to 1, alternating strings of both large and small spheres are observed. For asymmetric dumbbells, we investigate both the effect of size ratio and dipole moment ratio, leading to a large variety of cluster shapes, including chiral clusters.
authors.affiliation: Soft Condensed Matter, Debye Institute for NanoMaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands. f.smallenburg@gmail.com
authors.forename: Frank
authors.initials: F
authors.lastname: Smallenburg
authors.forename: Hanumantha Rao
authors.initials: HR
authors.lastname: Vutukuri
authors.forename: Arnout
authors.initials: A
authors.lastname: Imhof
authors.forename: Alfons
authors.initials: A
authors.lastname: van Blaaderen
authors.forename: Marjolein
authors.initials: M
authors.lastname: Dijkstra