Selective assemblies of giant tetrahedra via precisely controlled positional interactions

Abstract

Self-assembly of rigid building blocks with explicit shape and symmetry is substantially influenced by the geometric factors and remains largely unexplored. We report the selective assembly behaviors of a class of precisely defined, nanosized giant tetrahedra constructed by placing different polyhedral oligomeric silsesquioxane (POSS) molecular nanoparticles at the vertices of a rigid tetrahedral framework. Designed symmetry breaking of these giant tetrahedra introduces precise positional interactions and results in diverse selectively assembled, highly ordered supramolecular lattices including a Frank-Kasper A15 phase, which resembles the essential structural features of certain metal alloys but at a larger length scale. These results demonstrate the power of persistent molecular geometry with balanced enthalpy and entropy in creating thermodynamically stable supramolecular lattices with properties distinct from those of other self-assembling soft materials.

Dodecagonal quasicrystalline order in a diblock copolymer melt

“…Xie et al predict the occurrence of two Frank-Kasper phases, σ and A15, separated from the disordered state by the BCC phase with increasing segregation strength (i.e., at higher χN) in asymmetric AB diblock copolymers and AB m miktoarm block copolymers (26). The A15 phase (Pm3n) is an additional periodic quasicrystal approximant Frank-Kasper phase formed in a variety of self-assembling soft materials (22,(27)(28)(29). The SCFT calculations implicate asymmetry in the block statistical segment lengths as a key parameter, predicting that a minimal degree of asymmetry is required (b A > 1.5b B for AB diblocks) for a stable σ phase window to occur at f A < 1/2.…”

Low-symmetry sphere packings of simple surfactant micelles induced by ionic sphericity

“…More recently, FK A15 and σ phases were documented in thermotropic LCs of wedge-shaped dendrons (18)(19)(20), linear diblock and multiblock polymers (21, 22), and giant shape amphiphiles (2, 23). These studies culminated in the discovery of soft, dodecagonal QCs (23-26), for which the A15 and σ phases are 3D periodic approximants.Many of the previously reported soft matter FK phases optimize the van der Waals packing of hairy, uncharged particles that fill space at constant density, while minimizing unfavorable interfacial interactions between the particle cores and coronae (2,17,19,21). In this paper, we describe the spontaneous formation of a new, direct LLC FK σ phase by simple ionic surfactant micelles in water.…”

“…Many of the previously reported soft matter FK phases optimize the van der Waals packing of hairy, uncharged particles that fill space at constant density, while minimizing unfavorable interfacial interactions between the particle cores and coronae (2,17,19,21). In this paper, we describe the spontaneous formation of a new, direct LLC FK σ phase by simple ionic surfactant micelles in water.…”

“…The first FK A15 (15) and C15 (16) phases in ionic surfactant and lipidic LLCs were identified over 30 y ago, yet the principles governing their formation remain poorly understood (17). More recently, FK A15 and σ phases were documented in thermotropic LCs of wedge-shaped dendrons (18)(19)(20), linear diblock and multiblock polymers (21,22), and giant shape amphiphiles (2,23). These studies culminated in the discovery of soft, dodecagonal QCs (23)(24)(25)(26), for which the A15 and σ phases are 3D periodic approximants.…”

“…Driven by noncovalent interactions between constituents, block polymers (1), giant shape amphiphiles (2), thermotropic liquid crystals (LCs) (3), lyotropic liquid crystals (LLCs) (4), and colloids (5) exemplify soft matter systems that spontaneously form periodic 1D lamellar phases, 2D columnar structures, and 3D packings of spherical particles. Columnar and spherical phases are useful as templates for mesoporous heterogeneous catalysts (6) and as microscale photonic bandgap materials (7).…”