Prediction of Failure Properties of Polymer Network Formed Under Free Radical and Atom Transfer Radical Polymerizations

We present results of a study combining graph theory with coarse-grained molecular dynamics simulations to compare the failure properties of randomly cross-linked polymer networks synthesized by either free radical (FRP) or atom transfer radical (ATRP) polymerizations. We find that while different polymerization mechanisms lead to varied distributions of strands, dangling chains, and primary and higher-order loops, the failure processes of these homogeneous polymer networks exhibit similar characteristics. We demonstrate that polymer strands with higher geodesic edge betweenness centrality (GEBC) values, as compared to the system average, and shorter lengths are more susceptible to breaking under uniaxial tensile deformation. Additionally, we reveal that chain scission events occur randomly throughout the polymer network during the first half of the fracture process, while in the second half, highly correlated chain scission events lead to the complete rupture of the polymer network. Our results provide direct evidence of several key features of the rupture evolution process and offer valuable insights for the inverse design of network materials with desired fracture properties.