Self-Organization of Coil−Ring−Coil Structures into Tubular Supramolecular Polymer Brushes: Synthesis, Morphology, and Growth

Shape-persistent macrocycles based on the phenylene−ethynylene−butadiynylene backbone with extraannular amino groups were synthesized by the oxidative dimerization of the corresponding (BOC-protected) half-ring bisacetylenes. ABA block structures with a central rigid macrocycle and a flexible periphery (oligoalkyl and oligostyryl groups) were subsequently obtained by carbodiimide directed coupling of the macrocyclic diamines with the corresponding carboxylic acids. Depending on the solvent, an aggregation of the compounds toward tubular supramolecular polymer brushes could be induced. Cryogenic transmission electron microscopy and small-angle neutron scattering reveal the tubelike aggregates in solution. Atomic force microscopy confirms the morphology of these aggregates after casting onto surfaces. The aggregate growth occurs remarkably slowly. Solvophobic interactions—good solubility of the flexible substituents and weak solubility of the rigid macrocycle—combined with the oblate shape of the latter are determined as driving forces for the directed self-organization.