Flow-driven translocation of micelles self-assembled from amphiphilic diblock copolymers through a nanochannel is studied by using hybrid lattice-Boltzmann molecular dynamics simulations. It is discovered that the structure of the translocating micelles depends on their initial sizes. Intact translocation occurs for small micelles, whereas fragmented translocation takes place for large micelles. The fragmented micelles reassemble to form an intact micelle after translocation. Coexistence of these two translocation modes is observed when the size of the initial micelle core is similar to that of the nanochannel. The critical translocation flow flux, at which the probability of translocation equals to 0.5, is found to increase rapidly with the aggregation number of the initial micelles in the intact translocation regime, whereas it remains approximately a constant in the fragmented translocation regime. The number of fragmented translocating micelles is found to be a linear function of the aggregation number. These findings provide an understanding of the dynamics of micelle translocation.

Precise control of self-assembled structures in solution by tailoring molecular architecture is of great significance for the utilization of amphiphilic block copolymers. Inspired by the topological design principle via regulating the effect of spontaneous curvature in bulk, here, we focus on the self-assembly behavior of A′(A″B) n miktoarm star copolymer in dilute solution with tunable molecular architecture and spontaneous curvature through changing architectural parameters, including the volume fraction of A-blocks (f), the ratio of volume fraction of A′-block to the total A-blocks (τ), and the arm number (n). We use dissipative particle dynamics to investigate the phase behavior and self-assembled morphologies of A′(A″B) n copolymer in terms of τ and f in the B-selective and A-selective solvents, which exhibit notable differences due to the opposite effect of molecular spontaneous curvature. The stability region of morphologies with low interfacial curvature, such as vesicular structures, is relatively small in the B-selective solvent while that is expanded remarkably in the A-selective solvent. Compared with the monotonic shift of phase boundary between micellar structures and vesicular structures with τ in the B-selective solvent, the phase boundary shifts nonmonotonically in the A-selective solvent, with the appearance of more complex structures. It is noteworthy that the effect of bridge conformation of A″-blocks also greatly affects the self-assembly behavior in solution, and the longer A″-blocks promote the formation of vesicular structures and complex aggregates of assemblies. Moreover, the decrease of copolymer solubility caused by the effect of steric hindrance originating from molecular architecture has a tendency to drive the morphological transition from simple vesicles to compound vesicles in the A-selective solvent. Thus, by tuning the architecture of A′(A″B) n in different solutions, the effects of three mechanisms involving molecular curvature, bridge conformation, and copolymer solubility can be synergistically regulated to obtain abundant and desired nanostructures. These results deepen the understanding of the molecular design of amphiphilic block copolymers and provide theoretical guidance for preparing required morphologies in experiments.