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

Abstract

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 amphiphilicitydriven clusters in the system using the number density ρ N , the temperature T, the fraction of solvophobic monomers α, and the stiffness of the polymer rings κ 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.

Recent advances on the structure–properties relationship of multiblock copolymers

“…The authors pay a particular attention to the ability of star polymers to bridge distinct red domains as a function of the total number of arms M, and among them, the ones connected to the "first cell" m appearing in green. In Figure 6B4, their analysis emphasizes that the most probable conformation as well as the position of the star's center evolve with increasing the number of (2 and 3) Assembly of rings containing, respectively, 20% and 50% of (red) attractive units, adapted from Reference [136] arms. In particular, the configuration presented in Figure 6B2, that is, m ¼ 4 seems to be the most probable when M is fixed to 9, implying the displacement of the star center to a position being equidistant from three red spheres, leading to a maximum of bridging degree.…”

“…"Lighter" computational methods such as SCFT-oriented simulations evoked in Section 2.1 appear therefore in this context as a great alternative. In Figure 6, we have adapted recent results from References [81,133,136] focusing on the link between the molecular topology and the resulting microphase separation for linear MBCs, star MBCs with diblock arms, and diblock ring polymers, respectively.…”

“…Also, it requires to compute interactions for the different couples of beads, that is, AA, AB and BB resulting in a minimum of five different potentials to be defined. Once fixed the model parameters and the chains topology (linear, 132,133 star, 81,134 ring, 135,136 …), the simulation box is equilibrated at high temperature. One can then focus on the phase separation occurring upon cooling, by following the variation of volume (or enthalpy).…”

“…A last illustration of the structural richness of block copolymers beyond the usual linear diblock chains is that of amphiphilic "Janus" ring polymers proposed by Jehser and Likos. 136 Although the authors do not deal, strictly speaking, with MBCs in this case, we believe that their work is worth to highlight since it focuses on a recently developed polymer topology, mostly restricted to homopolymers so far. [145][146][147] The investigation concerns the self-assembly of Janus rings in solution varying the relative fractions of A and B species, the ring flexibility, the solution concentration and the temperature.…”

Hyperheavy spherical and toroidal nuclei: the role of shell structure

“…There are numerous examples but let us mention only some of them. Stable toroidal structures (micelles) play an important role in the amphiphilic polymers in large parts of the parameter space spanned by the degree of amphiphilicity, the temperature, the density and the molecular stiffness with respect to bending [6]. The wave propagation on the surface of the torus represents a vivid example of light behavior on curved surface of manifolds with interesting topologies and has potential applications in photonic structures [7].…”