Individual single-walled carbon nanotubes (SWCNTs) have thermal conductivity that is several times higher than copper. However, once researchers start to assemble SWCNTs into macroscale composites, fibers or films, they notice that thermal conduction drops significantly. Employing in situ transmission electron microscopy, researchers visualized a colossal anisotropy of thermal conductivity of nanoscale materials. The team says that their methodology to visualize nanoscale thermal ...