Aggregation shapes of amphiphilic ring polymers: from spherical to toroidal micelles

The self-assembly of Janus ring polymers is studied via a coarse-grained molecular dynamics employing a bead spring model including bending rigidity contributions to the Hamiltonian. We examine the formation and the morphology of amphiphilicity-driven clusters in the system using the number density rho(N), the temperature T, the fraction of solvophobic monomers alpha, and the stiffness of the polymer rings kappa as control parameters. We present a quantitative analysis of several characteristics for the formed clusters of Janus rings. Measured quantities include the distribution of the cluster size M-C and the shape of the clusters in the form of the prolate/oblate factor Q and shape factors sf. We demonstrate Janus rings form polymorphic micelles that vary from a spherical shape, akin to that known for linear block copolymers, to a novel type of toroidal shape, and we highlight the role played by the key physical parameters leading to the stabilization of such structures. Grapical abstract