Diblock Rings as Topological Adhesives at Immiscible Polymer Interfaces

Disparate polymers often do not mix well, and the resulting immiscible interfaces are mechanically weaker than the bulk, which is undesirable for many technological applications. Large-scale molecular simulations are performed to demonstrate the effectiveness of diblock ring polymers as a new type of adhesive for immiscible polymer interfaces. The peak stress σ_p and the failure strain γ_p upon shear deformation approach the bulk values with increasing diblock ring length and coverage. Breaking the diblock rings into pairs of diblock linear chains creates a reference system for comparison. The diblock rings increase both σ_p and γ_p compared to the diblock linear chains at the same coverage. Further topological analysis based on the Gauss Linking Number reveals that the threading of diblock rings by linear chains from the two opposite sides is the key mechanism for stronger adhesion, which is analogous to the hook-and-loop process in Velcro tape.