Coarse‐Grained Molecular Dynamics and Persistent Homology Analysis of Crosslinker Effects on Polymer‐Film Deformation

The effect of crosslinkers on the uniaxial tensile deformation of polymer films has been investigated using coarse‐grained molecular dynamics simulations. The uniaxial tensile simulations showed that increasing the number of crosslinks enhanced the stress in the plastic deformation region through strain hardening, whereas the stress response in the elastic deformation region was hardly affected. Even when the crosslink structure was varied by changing the number of crosslinks formed on each coarse‐grained particle or by introducing multifunctional crosslinkers, the stress–strain behavior was mainly governed by the total number of crosslinks formed in the polymer film. This result suggests that multi‐functionalization of crosslinkers may provide comparable mechanical reinforcement while reducing the concentration of crosslinkers. Persistent homology analysis of the crosslinked polymer films revealed characteristic ring structures in the persistence diagrams corresponding to the crosslink length. During tensile deformation, these ring structures were maintained and stretched, and the deformation of the crosslinked network was consistent with the increase in stress in the plastic deformation region. These results demonstrate that persistent homology analysis can explicitly capture networks originating from crosslink structures and may serve as an effective structural analysis method for crosslinked polymer films.