Exploring Cross‐Link Density and Additive Effects on Mechanical and Morphological Behaviors of Cross‐Linked Polymers

Abstract Cross‐linked thermoset polymeric materials are widely used in various engineering applications due to their excellent mechanical properties, thermal stability, and chemical resistance. Recent research highlights the role of cross‐link density and additives in influencing segmental dynamics and thermomechanical behavior of polymers. This study employs coarse‐grained molecular dynamics (CG‐MD) simulations to explore the thermomechanical and morphologic behaviors of cross‐linked polymers with molecular additives. Specifically, it is systematically investigated how cross‐link density ( c ) and different additive concentrations ( m ) affect key glass‐forming characteristics, along with the resulting changes in mechanical and morphologic properties of network materials as they approach their glass transition temperatures ( T g ). Relatively weaker interaction between the polymer network and additives can lead to additive aggregation, significantly affecting the morphology and T g as the m increases. Increasing c leads to an increase in both T g and fragility while increasing m decreases them. The simulation reveals that both c and m moderately influence the mechanical properties (i.e., shear and tensile modulus) of cross‐linked polymers with additives. This study provides valuable insights into how cross‐link density and additive concentrations influence glass‐forming and morphological behaviors, offering a molecular design strategy for developing advanced cross‐linked thermosets.