Probing the limit of one-dimensional heat transfer under extreme bending strain

Abstract

Theoretically, when a one-dimensional (1D) ballistic thermal conductor is mechanically bent beyond its elastic limit, nonlinear structural buckling will develop and reduce the transmission of phonons. However, because of 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 a previously inaccessible experimental regime. Surprisingly, even when the SWCNTs are bent far beyond their critical angles and curvatures, their thermal conductivities remain intact under cyclic bending. Moreover, the observed robustness of heat transfer is found to be independent of structural kinks, defects, dislocations, bending angles, or curvatures. Our results demonstrate that SWCNTs are exceptional 1D thermal conductors capable of sustaining high transmission of phonons under extreme bending strain.