Kinetic Control over Social and Narcissistic Self‐Sorting from Multicomponent Mixtures in Seed‐Initiated Supramolecular Polymerization by Fine‐Tuning of Steric Effects

Abstract Supramolecular polymers offer an intriguing possibility to transfer molecular properties from the nano‐ to the mesoscale. Towards this achievement, seed‐initiated supramolecular polymerization has emerged as a powerful tool, as it prevents unlimited growth and enables size control of the assembly outcome. However, the potential application of the seeding method in the context of complex supramolecular systems is hitherto unclear. Herein we demonstrate that minute differences in molecular design in direct proximity to intermolecular recognition sites govern the molecular packing and in turn dictate the efficacy of seeded polymerization processes. We introduce a stepwise increase in steric demand in the central amino acid residue of a diamide system, which gradually increases the rotational displacement within the aggregated state. This fine‐tuning of the molecular packing directly affects the propensity of the different aggregates to act as seeds for the other supramolecular synthons. In turn this allows us to selectively target specific trapped monomer states in binary mixtures for social or narcissistic seeded polymerization.