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This paper theoretically investigates phonon transport in aligned polymers with kinks using numerical evaluation of thermal conductivity. They find that for strongly aligned polymers, heat transport becomes superdiffusive at long lengths, with thermal conductivity scaling as $\kappa \propto L^{1/3}$. At shorter lengths, thermal conductivity exhibits non-monotonic behavior due to ballistic transport and Anderson localization.
Kinks in aligned polymers don't just reduce thermal conductivity, they induce superdiffusive heat transport at long lengths, scaling conductivity with length as $L^{1/3}$.
Thermal conductivity of aligned polymer molecules can be exceptionally high along the alignment direction due to energy transport through strong covalent bonds. At the same time, it is highly sensitive to molecular conformation, varying by orders of magnitude as a result of gauche kinks. Here, we theoretically investigate phonon transport in kinked polymers by numerically evaluating thermal conductivity and interpreting the results in terms of phonon scattering from randomly distributed kinks. For strongly aligned polymers with restricted deviations from a linear backbone, we find that heat transport becomes superdiffusive at long lengths, with thermal conductivity scaling as $\kappa \propto L^{1/3}$. At shorter lengths, thermal conductivity exhibits non-monotonic behavior: it increases at very short scales due to ballistic transport of almost all phonons, then decreases at intermediate lengths due to the Anderson localization of most phonon modes. These results are consistent with experiments and molecular dynamics simulations, and they elucidate the microscopic mechanisms governing heat transport in polymers.
