  This work summarizes recent progress on the thermal transport properties of
three-dimensional (3D) nanostructures, with an emphasis on experimental
results. Depending on the applications, different 3D nanostructures can be
prepared or designed to either achieve a low thermal conductivity for thermal
insulation or thermoelectric devices, or a high thermal conductivity for
thermal interface materials used in the continuing miniaturization of
electronics. A broad range of 3D nanostructures have been discussed, ranging
from colloidal crystals/assemblies, array structures, holey structures,
hierarchical structures, 3D nanostructured fillers for metal matrix composites
and polymer composites. Different factors that impact the thermal conductivity
of these 3D structures are compared and analyzed. This work provides an overall
understanding of the thermal transport properties of various 3D nanostructures,
which will shed light on the thermal management at nanoscale.
