Transition Kinetics of Self-Assembled Supramolecular Dodecagonal Quasicrystal and Frank–Kasper σ Phases in AB_n Dendron-Like Giant Molecules

Abstract

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 Pm3̅ n), 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.

Expanding quasiperiodicity in soft matter: Supramolecular decagonal quasicrystals by binary giant molecule blends

“…in 1984 ( 2 ), various QC alloys have been successively identified ( 3 , 4 ), and among them are three-dimensional (3D) icosahedral QCs (IQC) ( 5 – 10 ), 10-fold two-dimensional (2D) decagonal QCs (DQC) ( 11 – 14 ), and 12-fold 2D dodecagonal QCs (DDQC) ( 15 , 16 ). Recently, various condensed soft matters [e.g., block copolymers ( 17 – 21 ), dendrimers ( 22 , 23 ), and giant molecules ( 24 – 26 )] were also reported to form supramolecular DDQCs by a hierarchical assembling procedure. In these cases, the submesoatomic (molecular) units first aggregate into mesoatoms (i.e., the supramolecular spherical motifs compared to “atoms” in the metal alloy crystals), and then, the mesoatoms further assemble into the quasicrystalline superlattices (QC-SLs).…”

Dodecagonal quasicrystals of oil-swollen ionic surfactant micelles

“…These serendipitous discoveries highlight the obscure physical origins of their aperiodic order and marked preference for 12-fold symmetry. The question of whether or not soft DDQCs are thermodynamic equilibrium or metastable states also remains debated (6,8,10,17).…”

Multiple 2D crystal structures in bilayered lamellae from the direct self-assembly of 3D systems of soft Janus particles

“…In experiments, the bilayered lamellar phase, hexagonally packed cylinders, and even complex 3D Frank-Kasper phases have been observed in 3D self-assembly systems of amphiphilic building blocks including block copolymers [19][20][21] and giant amphiphiles. 19,[22][23][24][25] Recent research has also shown that amphiphilic Janus particles can self-assemble to form bilayered lamellar structures. [26][27][28][29][30][31][32] Moreover, as mentioned above, soft particles confined to two dimensions can generate a series of ordered crystals and Frank-Kasper phases.…”