Hierarchical control of internal superstructure, diameter, and stability of supramolecular and macromolecular columns generated from tapered monodendritic building blocks

The synthesis of the first generation AB₃ monodendrons 3,4,5-tris[6-alkyloxy-2-methyl-naphthyloxy]benzoic acid (with decyl, dodecyl, tetradecyl, and hexadecyl alkyl groups), 3,4,5-tris[4-(4′-dodecyloxyphenyl)benzyloxy]benzoic acid, their ω-hydroxy(tetraethylene glycol) esters, and the corresponding methacrylates and poly(methacrylate)s is described. All monodendrons and the corresponding polymers self-assemble into supramolecular columns that self-organize in a columnar hexagonal (Φ_h) thermotropic liquid crystalline (LC) phase. The characterization of their Φ_h phase by a combination of differential scanning calorimetry (DSC), thermal optical polarized microscopy, and X-ray diffraction experiments demonstrated an intracolumnar microsegregated model for these supramolecular structures. The role and the contribution of the aliphatic, aromatic, oligooxyethylenic, and polymethacrylate fragments to the formation and the control of the external diameter, the internal structure, and the stability of these supramolecular columns and of the Φ_h phase were quantitatively evaluated and demonstrated that the contribution of the aromatic component dominates over that of the other structural components both in the control of column diameter and in thermodynamic stability of the resulted Φ_h phase.