The New Limit of Heat Transfer Under Extreme Strain

Theoretical works have predicted that the thermal conductance of a deformed 1D system will start to decrease when the radius of curvature (R-c) is comparable to the phonon mean free path (l). However, due to limited mechanical strengths and short phonon mean free paths of most materials, no experimental works are capable of testing this fundamental limit of heat transfer so far. Here we utilize the superior mechanical strength and the high thermal conductivity of single-wall carbon nanotubes (SWCNTs) to investigate the heat transfer phenomena at previously inaccessible experimental regime. Surprisingly, the thermal conductivity of SWCNTs remains intact under cyclic strains and the ultimate condition of l/R-c > 10. Moreover, the robustness of heat transfer is found to be independent of defects, dislocations, structural kinks, bent angles, or bent curvatures. Our results demonstrate that SWCNTs are exceptional 1D thermal conductors with capabilities of going beyond the fundamental limit of heat transfer under extreme strain.