Tuning thermal conductivity of crystalline polymer nanofibers by interchain hydrogen bonding

Abstract

Polymers are widely used but they suffer from an apparent bottleneck of inefficient thermal conduction. Here, using non-equilibrium molecular dynamics, we demonstrate that hydrogen-bonded crystalline polymer nanofibers may have thermal conductivities 1–2 orders of magnitude higher than that of engineering polymers. Interchain hydrogen bonds serve as “soft grips” to restrict the torsional motion of polymer chains, leading to enhanced thermal conductivities. The degree of enhancement can be tuned by changing the density of hydrogen bonds, and the number of chains comprising the polymer nanofiber/nanosheet. Further analysis of the dihedral distribution and the phonon dispersion curves attribute such phenomena to the unique effects of hydrogen bonds in confining structural disorder and facilitating phonon transport. The study suggests an important way to tune the thermal conductivity of crystalline polymers.