Frank-Kasper (F-K) and quasicrystal phases were originally identified in metal alloys and only sporadically reported in soft materials. These unconventional sphere-packing schemes open up possibilities to design materials with different properties. The challenge in soft materials is how to correlate complex phases built from spheres with the tunable parameters of chemical composition and molecular architecture. Here, we report a complete sequence of various highly ordered mesophases by the self-assembly of specifically designed and synthesized giant surfactants, which are conjugates of hydrophilic polyhedral oligomeric silsesquioxane cages tethered with hydrophobic polystyrene tails. We show that the occurrence of these mesophases results from nanophase separation between the heads and tails and thus is critically dependent on molecular geometry. Variations in molecular geometry achieved by changing the number of tails from one to four not only shift compositional phase boundaries but also stabilize F-K and quasicrystal phases in regions where simple phases of spheroidal micelles are typically observed. These complex self-assembled nanostructures have been identified by combining X-ray scattering techniques and real-space electron microscopy images. Brownian dynamics simulations based on a simplified molecular model confirm the architecture-induced sequence of phases. Our results demonstrate the critical role of molecular architecture in dictating the formation of supramolecular crystals with "soft" spheroidal motifs and provide guidelines to the design of unconventional self-assembled nanostructures.self-assembly | Frank-Kasper phases | quasicrystal phases | giant surfactants | POSS I n addition to the close-packing schemes of identical atoms (such as hexagonal close-packing and face-centered cubic), atoms with different radii and electronic states in metal alloys are able to pack into more complex phases composed of spheres, such as the Frank-Kasper (F-K) phases (1, 2), which combine the Frank lattice (icosahedron with a coordination number of 12) and the Kasper lattice (with higher coordination numbers of 14, 15, and 16). A few F-K phases such as the A15-(space group of Pm 3n) and σ-(space group of P4 2 /mnm) phases are periodic approximants of different quasicrystals. Quasicrystals, first identified in supercooled metal alloys, are aperiodic, and possess 5-, 7-, 8-, 10-, or 12-fold rotational symmetry but no long-range translational periodicity (3-5). Stabilization of these phases in metals originates from both geometric factors and the tendency to enhance low orbital electron sharing due to fewer surface contacts among the atoms (6).F-K phases have also been identified in soft-matter systems, including small-molecule surfactants (7-9), block copolymers (10-12), dendrimers (13-15), liquid crystals (16, 17), colloidal particles (18), and, very recently, molecular giant tetrahedra (19). In contrast to metal alloys that use atoms as the motifs, organic/hybrid molecules first self-assemble into spheroidal motifs...

|Macromolecules 2011, 44, 3062-3072 Macromolecules ARTICLE (7) There is substantial band broadening caused by some factors not well understood at this moment. An in-depth investigation is needed in order to improve TGIC resolution capability.

This work explores the mechanism whereby a cationic diimine Pd­(II) complex combines coordination insertion and radical polymerization to form polyolefin–polar block copolymers. The initial requirement involves the insertion of a single acrylate monomer into the Pd­(II)–polyolefin intermediates, which generate a stable polymeric chelate through a chain-walking mechanism. This thermodynamically stable chelate was also found to be photochemically inactive, and a unique mechanism was discovered which allows for radical polymerization. Rate-determining opening of the chelate by an ancillary ligand followed by additional chain walking allows the metal to migrate to the α-carbon of the acrylate moiety. Ultimately, the molecular parameters necessary for blue-light-triggered Pd–C bond homolysis from this α-carbon to form a carbon-centered macroradical species were established. This intermediate is understood to initiate free radical polymerization of acrylic monomers, thereby facilitating block copolymer synthesis from a single Pd­(II) complex. Key intermediates were isolated and comprehensively characterized through exhaustive analytical methods which detail the mechanism while confirming the structural integrity of the polyolefin–polar blocks. Chain walking combined with blue-light irradiation functions as the mechanistic switch from coordination insertion to radical polymerization. On the basis of these discoveries, robust di- and triblock copolymer syntheses have been demonstrated with olefins (ethylene and 1-hexene) which produce amorphous or crystalline blocks and acrylics (methyl acrylate, ethyl acrylate, n-butyl acrylate, and methyl methacrylate) in broad molecular weight ranges and compositions, yielding AB diblocks and BAB triblocks.

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