The arrangement of nanoscale building blocks into patterns
with
microscale periodicity is challenging to achieve via self-assembly
processes. Here, we report on the phase-transition-driven collective
assembly of gold nanoparticles in a thermotropic liquid crystal. A
temperature-induced transition from the isotropic to the nematic phase
under anchoring-driven planar alignment leads to the assembly of individual
nanometer-sized particles into arrays of micrometer-sized agglomerates,
whose size and characteristic spacing can be tuned by varying the
cooling rate. Phase field simulations coupling the conserved and nonconserved
order parameters exhibit a similar evolution of the morphology as
the experimental observations. This fully reversible process offers
control over structural order on the microscopic level and is an interesting
model system for the programmable and reconfigurable patterning of
nanocomposites with access to micrometer-sized periodicities.