The monomers (M) are composed of 7 beads (Figure ) disposed in a planar hexagonal shape (see Methods and Supporting Information, SI, for details), and interact mostly via the central beads, which are strongly attracted to each other. The six lateral beads are instead weakly interacting and, shielding the attraction between core beads at the monomer sides, impart directionality to the self-assembly. The non-bond interactions between beads are determined by Lennard-Jones (LJ) potentials, with fixed radius (σ ) for all the beads, and two different values of interaction strength (ε): large (several k B T s) for the interaction between central beads, and small (a fraction of k B T ), when lateral beads are involved (Figure ). The dynamics of the system is modelled via Langevin equations of motion. The effect of the solvent is represented implicitly, i.e. the non-bond potential between the beads accounts for both solute-solute and solute-solvent interactions, while friction and fluctuations are rendered by Langevin dynamics. As the interaction between monomers is mainly governed by directional, specific attraction, this model mimics supramolecular polymers where (i) monomers self-assemble in a good solvent, and (ii) the monomer shape and features favor mutual directional aggregation. We simulated 500 M monomers in a fixed cubic volume, at fixed temperature (T = 300 K). Starting from randomly distributed monomers, one-dimensional fibres spontaneously formed during CG-MD (Figure ), reaching an equilibrium that depends on the stacking attraction between monomer cores (the interaction strength ε between the central beads). We first compared CG-MD simulations of the same system (ε = 40 kJ mol -1 ), starting from two different configurations (Figure ),