Deformation and Mechanics of Graft Block Copolymer Compatibilized Polymer Blends

We report coarse-grained molecular dynamics simulations of glassy A/B polymer interfaces compatibilized by AB graft copolymers. Building on our recent work on modeling the toughness of these interfaces, we focus here on the effects of copolymer architecture and loading on the stress-transfer mechanisms and entanglement dynamics. Low loadings produce instantaneous interfacial separation, where trapped entanglements effectively secure the graft backbone while the grafts are pulled out. In contrast, high loadings lead to distinct, architecture-dependent stress-transfer mechanics and a transition toward backbone-side failure, driven by a larger topological barrier to forming trapped entanglements. Junction density controls the trade-off between voiding and strain hardening as the system is strained, suggesting that tuning this parameter can be an effective compatibilization strategy. Finally, we compare the mechanical performance of graft copolymers and linear multiblock copolymers, bringing to the fore the impact of single- and double-tethered junctions.