Interfacial behavior of linear, ring, and [2]catenane PEO at the water/vapor interface

We investigated whether polymer topology modulates the interfacial behavior of single poly(ethylene oxide) (PEO) chains at the water/vapor interface using all-atom molecular dynamics simulations. Linear, ring, and [2]catenane architectures were simulated under identical conditions, and their dynamics are quantified via interfacial residence time, in-plane and out-of-plane components of the radius of gyration, orientational order, water-contact fraction, and lateral diffusion, yielding a comparative dynamical fingerprint. To interpret these trends, we computed potentials of mean force (PMFs) for translating the chain center of mass across the interface and compare salient PMF features (minima, barriers) with the conformational metrics to assess the extent of correspondence. To extend beyond atomistic length and time scales, we employ a complementary coarse-grained bead–spring model to survey molecular weight, temperature, interfacial tension, and topology. Taken together, these results clarify how loop closure and mechanical interlocking influence single-chain persistence and mobility at liquid interfaces.