The interacting hexagonal unit M is composed of seven beads, six shielding beads at the vertices of a regular hexagon and a central core bead, as depicted in Figure . The flat hexagonal geometry of the M monomer model is imposed by bonded interactions defined by harmonic bonds: the force constant between the nearest neighbor beads is 20000 kJ mol -1 nm -2 and the equilibrium length is 0.47 nm. In order to keep the M hexagons planar, each shielding bead is also connected with the one at the opposite vertex of the hexagon by a harmonic bond with equilibrium length 0.94 nm and force constant of 15000 kJ mol -1 nm -2 . The non-bonded interactions between beads are defined by Lennard-Jones (LJ) potentials, with constant σ = 0.47 nm and variable interaction strength ε. All the shielding beads interact weakly with each other and with the core beads (ε = 0.2 kJ mol -1 ), while the interaction between core beads are stronger, with an interactions strength that varies across simulated systems (40 kJ mol -1 , 45 kJ mol -1 or 50 kJ mol -1 ). Such LJ parameters, plus the geometry of the M monomers, determine the tendency of the M monomers to interact directionally. All the model settings and parameters used herein are provided in the SI (in .GRO and .ITP GROMACS format).