Flow-driven translocation of polymer vesicle through a nanochannel

Flow-driven translocation of a polymer vesicle self-assembled from amphiphilic diblock copolymers through a nanochannel is studied using hybrid Lattice-Boltzmann Molecular Dynamics simulations. Three translocation modes are discovered: a single vesicle, small vesicles, and tiny micelles in sequence, respectively, as the width of the nanochannel is decreased, which is confirmed by the self-consistent field theory calculations. Accordingly, spherical vesicles, ellipsoidal vesicles, and worm-like micelles are formed sequentially after crossing the nanochannel. More importantly, we find that the critical flow rate monotonically decreases as the ratio of the polymer vesicle size and the width of the nanochannel decreases until it approaches 1. Our results provide a basis for characterizing the stability of vesicles or sorting vesicles with different sizes and also point to a new idea of regulating spherical vesicles to ellipsoidal vesicles or worm-like micelles.