Molecular Dynamics Simulation of Thermodynamic Properties of Functionalized Carbon Nanotubes Filled Polyimide Composites.

As lithium battery technologies advance, superior polyimide-based materials are urgently required. However, the microscopic mechanism by which CNT surface chemistry governs polyimide (PI) enhancement remains a challenge. This study employs molecular dynamics simulations to investigate how functionalizing carbon nanotubes (CNTs) with different surface groups (-COOH, -NH2, -OH) enhances the thermal and mechanical properties of PI composites for advanced engineering applications. The simulation results reveal that all functionalized CNTs improve the composite's properties, with carboxyl-modified CNTs providing the most significant enhancement. Specifically, a grafting density of 20-COOH yielded optimal performance, achieving a Young's modulus of 5.811 GPa and a tensile strength of 186 MPa. These improvements originate from strengthened interfacial interactions between the functionalized CNTs and the PI matrix, which restrict molecular chain mobility and reduce free volume. This work provides a theoretical foundation for designing high-performance PI-based nanocomposites through tailored nanofiller surface chemistry.