Statics of Diblock Ring Polymers in Lamellar Phase: A Study Combining Molecular Simulations and Scaling Analysis

Ingenious synthesis and precise characterization of non-concatenated ring polymers propel the idea of using polymer topology as a new pathway to achieve desirable nanostructures for polymer-based templating and membrane applications. Extensive molecular simulations are performed to study the static properties of diblock ring polymer melts in the lamellar phase. The self-similar dynamics of non-concatenated ring polymers, which are much faster than the entangled dynamics of linear polymers, facilitate the transition from the disordered phase to the lamellar phase. The lamellar spacing d and the interfacial width w for the structure equilibrated at constant pressure are computed as functions of both the ring polymer contour length N and the χ parameter for the interactions between the two blocks. The simulation results agree with the scaling analysis based on the self-similar loopy globular conformations of non-concatenated ring polymers. A further comparison with the lamellar phase of diblock linear polymer melts with chain length N/2 shows that d is reduced for the diblock ring polymers at the same value of χ, manifesting the topological interactions that make non-concatenated ring polymers more compact than the random-walk conformations.