Transition Kinetics of Self-Assembled Supramolecular Dodecagonal Quasicrystal and Frank–Kasper σ Phases in AB n Dendron-Like Giant Molecules
A series of noncrystalline AB n dendron-like giant molecules DPOSS–MPOSS n (n = 2–6, DPOSS: hydrophilic polyhedral oligomeric silsesquioxane (POSS) cage; MPOSS: hydrophobic POSS cage) were synthesized. These samples present a thermodynamically stable phase formation sequence from the hexagonal cylinder phase (plane group of P6mm), to the Frank–Kasper (F–K) A15 phase (space group of Pm$\overline{3n}$), and further to the F–K σ phase (space group of P4 2 /mnm), with increasing the number of MPOSS in a single molecule (n, from 2 to 6). Moreover, for DPOSS–MPOSS 5 and DPOSS–MPOSS 6 , an intriguing dodecagonal quasicrystal (DQC) structure has been identified and revealed as a kinetic favorable metastable phase at lower temperatures, while the thermodynamically stable phase is the σ phase. The detailed investigation of the transition kinetics between the DQC and σ phase in these samples makes it possible to identify how the self-assembly directs the phase transition in terms of molecular and supramolecular aspects.