Connection between polymer chain length, adhesion, and temperature with mechanical properties and glass transition temperature of graphene/polymer nanocomposites

In polymer/graphene nanocomposites, the interaction between polymer chains and graphene nanosheets is an important factor that influences their mechanical and thermal properties. In this study, molecular dynamics simulations were used to investigate the effects of polyethylene (PE) chain length and polymer–graphene adhesion at different temperatures on the mechanical properties and glass transition temperature of polyethylene/graphene (PE/GNs) nanocomposites. The results showed that the Young’s modulus of the nanocomposites increased from 1.0 ± 0.08 to 1.4 ± 0.07 GPa as the polymer chain length increased. Similarly, the interaction energy (adhesion) rose from 0.16 ± 0.009 to 0.26 ± 0.008 J/m ² with longer polymer chains. Analysis of MSD diagrams revealed that the mobility of polymer chains increased with chain length from 6 to 21 Å. Moreover, nanocomposites with longer chains exhibited a larger radius of gyration (Rg), indicating a more expanded structure. The glass transition temperature (Tg) was also affected by chain length. Nanocomposites with 21 Å chains had the highest Tg (265 ± 2.2 K), while those with 6 Å chains showed the lowest (232 ± 2.3 K). Additionally, increasing the temperature from 150 to 500 K resulted in a decrease in Young’s modulus, interaction energy, and radius of gyration.