Molecular Dynamics Simulation of Thermodynamic Properties of Polydimethylsiloxane Modified by KH550-grafted Graphene
The present work focused on the effects of silane coupling agent-grafted graphene on the properties of polydimethylsiloxane(PDMS),and carried out molecular dynamics modelling and simulation for pure PDMS,PDMS modified by non-grafted graphene,and PDMS modified by KH550-grafted graphene(with graft intensities of 6％and 12％),in order to analyze the thermodynamic property improvement induced by modification.The simulation indicated that either non-grafted graphene or KH550-grafted graphene has positive influence on thermodynamic properties of PDMS such as thermal conductivity,glass transition temperature(Tg),free volume,mean square displacement,and water molecules'diffusion coefficient and H2O-composite binding energy.In the water-containing models,6％and 12％KH550-grafted graphene modified PDMSs could achieve improvements in thermal conductivity(at 250 K)of 25.6％and 21.6％,respectively,and Tg rises of 70 K and 77 K,respectively,compared with pure PDMS.The comparison between the water-containing and non-water models of the KH550-grafted graphene modified PDMS confirmed that water molecules results in increase in mean square displacement,and reductions in Tg and free volume,and the H2O molecule diffusion coefficient and H2O-composite binding energy differs with varying temperature and graft intensity.The output of this work may provide useful information for future studies on mitigating the impact of flashover voltage on electric system,and theoretical support for the development of transmission line de-icing and hydrophobic materials.
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维普
