Dodecagonal quasicrystals of oil-swollen ionic surfactant micelles

Abstract

A delicate balance of noncovalent interactions directs the hierarchical self-assembly of molecular amphiphiles into spherical micelles that pack into three-dimensional periodic arrays, which mimic intermetallic crystals. Herein, we report the discovery that adding water to a mixture of an ionic surfactant and n-decane induces aperiodic ordering of oil-swollen spherical micelles into previously unrecognized, aqueous lyotropic dodecagonal quasicrystals (DDQCs), which exhibit local 12-fold rotational symmetry and no long-range translational order. The emergence of these DDQCs at the nexus of dynamically arrested micellar glasses and a periodic Frank–Kasper (FK) σ phase approximant sensitively depends on the mixing order of molecular constituents in the assembly process and on sample thermal history. Addition of n-decane to mixtures of surfactant and water instead leads only to periodic FK A15 and σ approximants with no evidence for aperiodic order, while extended ambient temperature annealing of the DDQC also reveals its transformation into a σ phase. Thus, these lyotropic DDQCs are long-lived metastable morphologies, which nucleate and grow from a stochastic distribution of micelle sizes formed by abrupt segregation of varied amounts of oil into surfactant micelles on hydration. These findings indicate that molecular building block complexity is not a prerequisite for the formation of aperiodic supramolecular order, while also establishing the generic nature of quasicrystalline states across metal alloys and self-assembled micellar materials.

Frank–Kasper Phases in Block Polymers

“…The second factor is potential connections between particle-forming phases across different classes of materials. Frank–Kasper phases have their origins in metallic alloys; the discovery of increasingly complicated crystal structures ultimately led to the development of general rules governing tetrahedral packing within these alloys by Frank and Kasper at the end of the 1950s. , While Frank–Kasper phases remain most commonly found in such alloys, they also have been identified in an increasingly wide variety of soft matter in the past 30 years, including liquid crystals, − dendrimers, , sugar–polyolefins, and shape amphiphiles. − Is there an underlying mechanism governing the emergence of similar packing across such a wide variety of soft materials? If so, block polymers should prove to be the ideal system to probe those connections because block polymer thermodynamics are relatively straightforward and, in the long chain limit, have universal properties that simplify their description within a statistical mechanical framework .…”

Mesoscale Frank–Kasper Crystal Structures from Dendron Assembly by Controlling Core Apex Interactions

“…Colloidal particles’ analogy to single metal elements, however, breaks when the spherical particles are assemblies of oligomeric molecules . Not like the atoms or molecules in colloidal particles, the molecular chains in the spherical molecular assembly, for example, dendrons, , surfactants, − block copolymers, − and amphiphiles, , can migrate from a sphere to another to create two or multisized spheres and thus form complex low-symmetry structures that are similar to those found in metal alloys. − These mesoscale crystal structures include a dodecagonal liquid quasicrystal (DDQC) and the Frank–Kasper (FK) family phases.…”

An Accelerated Modular-Orthogonal Ni-Catalyzed Methodology to Symmetric and Nonsymmetric Constitutional Isomeric AB2 to AB9 Dendrons Exhibiting Unprecedented Self-Organizing Principles

“…Before the discovery of the Frank–Kasper A15 phase in supramolecular dendrimers ,,, followed by the σ-phase and LC quasicrystal, it was expected that soft spheres self-organize predominantly in face-centered cubic (FCC) and body-centered cubic (BCC) lattices . In the meantime Frank–Kasper phases were discovered also in block copolymers, surfactants, giant molecules, and DNA nanoparticles …”

“…The original self-assembling compounds were constructed from benzyl ether dendrons functionalized with aliphatic, fluorinated, semifluorinated, and oligooxyethylene fragments , and subsequently were expanded to other constructs to be discussed in more detail later. They led to the immediate discovery of helical self-organizations, Frank–Kasper phases, and soft quasicrystals that were subsequently found in many other forms of soft matter such as block copolymers, lipids, surfactants, giant molecules, and DNA-grafted nanoparticles. − More recently they evolved in biological membrane mimics and into a single component delivery system for mRNA . The dream of self-organized complex soft matter is to reach the perfection of periodic arrays self-organized from inorganic materials that are assembled from a small number of atoms as well as that of biological macromolecules that is self-organized from millions of atoms.…”