Brownian dynamics simulation study on the self-assembly of incompatible star-like block copolymers in dilute solution

We study the self-assembly of symmetric star-like block copolymers (A(x))(y)(B-x)(y)C in dilute solution by using Brownian dynamics simulations. In the star-like block copolymer, incompatible A and B components are both solvophobic, and connected to the center bead C of the polymer. Therefore, this star-like block copolymer can be taken as a representative of soft and deformable Janus particles. In our Brownian dynamics simulations, these "soft Janus particles'' are found to self-assemble into worm-like lamellar structures, loose aggregates and so on. By systematically varying solvent conditions and temperature, we build up the phase diagram to illustrate the effects of polymer structure and temperature on the aggregate structures. At lower temperatures, we can observe large worm-like lamellar aggregates. Upon increasing the temperature, some block copolymers detach from the aggregate; this phenomenon is especially sensitive for the polymers with less arms. The aggregate structure will be quite disordered when the temperature is high. The incompatibility between the two parts in the star-like block copolymer also affects the self-assembled structures. We find that the worm-like structure is longer and narrower as the incompatibility between the two parts is stronger.