Molecular Dynamics Insights Into Interfacial Cross‐Linking and Mechanical Reinforcement in Functionalized Carbon Nanotube/Bismaleimide Nanocomposites

ABSTRACT Bismaleimide (BMI) is a high‐performance thermosetting resin widely used in the fields of aerospace, machinery, and electronics due to its excellent mechanical properties and thermal stability. In this work, molecular dynamics simulations that incorporate cross‐linking reactions between carbon nanotubes (CNTs) and BMI are performed. These simulations evaluate the effects of the degree of functionalization (DF) and the volume fraction of CNTs ( f CNT ) on the mechanical properties of the nanocomposites and elucidate the underlying mechanisms. Elastic and shear moduli increase with DF, although functionalization distorts CNTs and reduces their intrinsic modulus. The resulting denser CNT–BMI cross‐linked network enhances stiffness of nanocomposites, with reinforcing effects outweighing CNT deformation‐induced weakening. Increasing f CNT also improves elastic modulus; compared with neat BMI, the modulus increases from 3.63 to 4.98 GPa at f CNT of 4.40%. This enhancement reflects direct CNT stiffening contributions, reduced matrix‐chain mobility (decreased diffusion coefficients), and denser cross‐linked network formation. Comparison with Halpin–Tsai predictions indicates the cross‐linking provides additional reinforcement beyond simple filler loading, particularly in the direction transverse to the CNT axis and at higher f CNT . These findings provide molecular‐level insights into structure–property relationships in CNT/BMI nanocomposites and guidance for interfacial design of high‐performance BMI‐based materials.