Molecular weight effects on chain pull-out fracture of reinforced polymeric interfaces

Using Brownian dynamics, we simulate the fracture of polymer interfaces reinforced by diblock connector chains. We consider the mushroom regime, where connector chains are grafted with low surface density, for the case of large pulling velocities. We find that for short chains the interface fracture toughness depends linearly on the degree of polymerization N of the connector chains, while for longer chains the dependence becomes N(3/2). Based on the geometry of the initial chain configuration, we propose a scaling argument that accounts for both short and long chain limits and the crossover between them.