Analysis of the Structure and the Thermal Conductivity of Semi-Crystalline Polyetheretherketone/Boron Nitride Sheet Composites Using All-Atom Molecular Dynamics Simulation.

Thermal transport simulations were performed to investigate the important factors affecting the thermal conductivity based on the structure of semi-crystalline polyetheretherketone (PEEK), and the addition of boron nitride (BN) sheets. The molecular-level structural analysis facilitated the prediction of the thermal conductivity of the optimal structure of PEEK reflecting the best parameter value of the length of amorphous chains, and the ratio of linkage conformations, such as loops, tails, and bridges. It was found that the long heat transfer paths of polymer chains were induced by the addition of BN sheets, which led to the improvement of the thermal conductivities of the PEEK/BN composites. In addition, the convergence of the thermal conductivities of the PEEK/BN composites in relation to BN sheet size was verified by the disconnection of the heat transfer path due to aggregation of the BN sheets.

Analysis of the effect of organic solvent-sheet interfacial interaction on the exfoliation of sulfur-doped reduced graphene oxide sheets in a solvent system using molecular dynamics simulations.

In this study, the effect of interfacial interaction between solvent and sheets on the exfoliation of sulfur-doped reduced graphene oxide (SrGO) sheets was studied, using molecular dynamics simulations. Four organic solvents of toluene, tetrahydrofuran, N-methyl-2-pyrrolidone, and sulfolane, were used in this simulation. An insertion simulation considering the size effect of insertion molecules was used to determine the insertion efficiency of the solvent molecules. The insertion efficiency of toluene was the best among the four solvents due to the influence of the effective thickness of the solvent. An exfoliation simulation considering electrostatic interaction was conducted to evaluate the exfoliation efficiency of the SrGO sheets. Unlike the insertion efficiency case, the sulfolane was found to have the best exfoliation efficiency among the four solvents, due to the strong electrostatic repulsion and weak attractive energy between the SrGO sheets. The exfoliation efficiency of the SrGO sheets was improved by increasing the sulfur content and the ratio of the thiol type to the total number of sulfur-doped groups. These results reveal that decreasing the attractive energy and increasing the electrostatic repulsion between the solvent and SrGO sheets are a useful way to improve the exfoliation efficiency of SrGO sheets.