Self-assembly of graft copolymers in backbone-selective solvents: a route toward stable hierarchical vesicles

We employ self-consistent field theory and dissipative particle dynamics simulation to investigate self-assembly of graft copolymers in a backbone-selective solvent. It is found that the graft copolymers are capable of forming hierarchical vesicles such as multilamellar vesicles and large-compound vesicles in dilute solution. The self-consistent field calculations demonstrate that the formed hierarchical vesicles are thermodynamically stable, due to the nature of the graft copolymers. In addition, the dissipative particle dynamics simulations reveal that the pathway of the spontaneous vesicle formation in an initially homogeneous dilute solution is hierarchical. Unilamellar vesicles are first formed along the "standard" pathway, then gradually coalesced to compound or multilamellar sub-vesicles, and finally organized into large-compound or multilamellar vesicles. The results demonstrate the possibility of using two-component copolymers to generate stable aggregates with complex structures, and suggest a versatile and promising route to obtain the advanced nanostructured materials.