  Applying an electric field to polarisable colloidal particles, whose
permittivity differs from that of the dispersing medium, generates induced
dipoles that promote the formation of string-like clusters and ultimately alter
the fluid mechanical and rheological properties. Complex systems of this kind,
whose electric-field-induced rheology can be manipulated between that of
viscous and elastic materials, are referred to as electrorheological fluids. By
dynamic Monte Carlo simulations, we investigate the dynamics of self-assembly
of dielectric nanocubes upon application of an electric field. Switching the
field on induces in-particle dipoles and, at sufficiently large field
intensity, leads to stringlike clusters of variable length across a spectrum of
volume fractions. The kinetics of switching from the isotropic to the
string-like state suggests the existence of two mechanisms, the first related
to the nucleation of chains and the second to the competition between further
merging and separation. We characterise the transient unsteady state by
following the chain length distribution and analysing the probability of
transition of nanocubes from one chain to another over time. Additionally, we
employ passive microrheology to gain an insight into the effect of the electric
field on the viscoelastic response of our model fluid. Not only do we observe
that it becomes more viscoelastic in the presence of the field, but also that
its viscoelasticity assumes an anisotropic signature, with both viscous and
elastic moduli in planes perpendicular to the external field being larger than
those along it.
