Tuning the polymer thermal conductivity through structural modification induced by MoS2 bilayers.

ABSTRACT

The present work refers to a physical and structural study of nanoconfined polymers in polymer-MoS2 nanocomposites as a function of MoS2-MoS2 interlayer distance. We applied reverse nonequilibrium molecular dynamics (RNEMD) simulations to investigate the thermal conductivity (λ) of polyamide oligomers confined by MoS2 bilayers. The results of this study indicate that thermal conductivity of polymer can be considerably enhanced when polymer chains are confined by MoS2 sheets, this behavior is more pronounced by charged surfaces. The presence of MoS2 surfaces leads to elongation as well as preferential alignment of polymer chains parallel to the MoS2 surfaces, which in turn results in higher order and denser packing of polymer content and hence larger thermal conductivity in comparison to the bulk polymer. Additionally, the analysis of the number of hydrogen bonds (HBs) in confined polymer chains suggests that a combined effect of the mentioned structural modification and enlarged values of HBs may cooperatively contribute to high polymer thermal conductivity, facilitating phonon transport. The results reported here suggest a significant way to design confined polymer-MoS2 composites for significantly improving thermal conductivity for a wide variety of applications.