Effect of hydrogen bonds on the thermal transport in a precisely branched polyethylene with ordered and amorphous structures

Hydrogen bonds are considered to be bridges in forming networks for heat transfer in polymers. Nevertheless, a large number of polymer systems with hydrogen bonds have very low thermal conductivity (TC). The role of hydrogen bonds in regulating TC of polymers is still beyond fully understood. Herein, we systematically investigate the effect of hydrogen bonds on the intrinsic TC of polymers with ordered and amorphous structures by using molecular dynamics simulations. The ordered polymer (termed as ar-P21AA) has lamella structure with stacked layers alternatively composed of aligned polymer chains and hydrogen-bonded functional groups, which provides an ideal model for studying hydrogen-bond-mediated heat transfer. We find that significant ITR exists at the interface composed of hydrogen-bonded carboxyl groups; nevertheless, ITR of that hydrogen-bonded interface is about 2 times smaller than that of a typical VdWs interface. The Role of hydrogen bonds in enhancing the interfacial thermal transport is analyzed. As for the amorphous ar-P21AA, increasing the hydrogen-bonding strength does not change much TC due to the invariance of stiffness and packing density of the structure, in terms of the minimum thermal conductivity model. A consequent effect on the chain morphology when introducing hydrogen bonds may be a factor to be considered for improving the thermal conductivity. The work provides insight into the design of thermally conductive polymers by introducing hydrogen-bonding interaction.