Diblock Rings\nas Topological Adhesives at Immiscible\nPolymer Interfaces

Disparate polymers often do not mix well, and the resulting\nimmiscible\ninterfaces are mechanically weaker than the bulk, which is undesirable\nfor many technological applications. Large-scale molecular simulations\nare performed to demonstrate the effectiveness of diblock ring polymers\nas a new type of adhesive for immiscible polymer interfaces. The peak\nstress σ<sub><i>p</i></sub> and the failure strain\nγ<sub><i>p</i></sub> upon shear deformation approach\nthe bulk values with increasing diblock ring length and coverage.\nBreaking the diblock rings into pairs of diblock linear chains creates\na reference system for comparison. The diblock rings increase both\nσ<sub><i>p</i></sub> and γ<sub><i>p</i></sub> compared to the diblock linear chains at the same coverage.\nFurther topological analysis based on the Gauss Linking Number reveals\nthat the threading of diblock rings by linear chains from the two\nopposite sides is the key mechanism for stronger adhesion, which is\nanalogous to the hook-and-loop process in Velcro tape.