Supramolecular dendritic liquid quasicrystals (original) (raw)
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Advanced Functional Materials, 2011
This article reviews the diversity of phase morphologies observed recently in starbranched liquid crystalline and polymeric compounds containing at least three immiscible segments. Bolaamphiphiles and facial amphiphiles with a rod-like aromatic core, two endgroups and one (T-shape) or two chains (X-shape) attached laterally to the core form numerous honeycomb-like liquid crystal phases, as well as a variety of novel lamellar and 3Dordered mesophases. Molecular self-organization is described in bulk phases and in thin films on solid and liquid surfaces, as well as in Langmuir-Blodgett films. The remarkably reversible formation of mono-and tri-layer films is highlighted. In the bulk, T-shaped "rod-coil" molecules without the appended end-groups form predominantly lamellar phases if the core is a straight rod, but the bent-core variety forms hexagonal honeycombs. Furthermore, selfassembly of "Janus"-type molecules, such as those with Y-shaped star mesogens bearing different mutually incompatible side-groups, is discussed. Also covered is the diversity of morphologies observed in miktoarm star terpolymers i.e. polymers with three different and 3 incompatible arms of well-defined lengths. A range of bulk phases with 3D or 2D order are observed, combining layers, cylinders and cocontinuous networks. Similarities and differences are highlighted between the liquid crystal morphologies on the 3-15 nm scale and the polymer morphologies on the scale 10-100 nm. A separate section is dedicated to computer simulations of such systems, particularly those using dissipative particle and molecular dynamics. Of special interest are the recently synthesised X-shaped tetraphilic molecules, where two different and incompatible side-chains are attached at opposite sides of the rod-like core. The tendency for their phase separation produces LC honeycombs with cells of different compositions that can be represented as paving a plane with different color tiles. The independent variation of chain length and "color" creates the potential for developing a considerable range of complex new 2d-and 3d soft nanostructures. Analogous X-shaped rodcoil compounds with unequal side groups are also of considerable interest, forming tubular lyotropic structures capable of confining strings of guest molecules. Contents 1 Introduction .
Hierarchical Self-Organization of AB n Dendron-like Molecules into a Supramolecular Lattice Sequence
ACS central science, 2017
To understand the hierarchical self-organization behaviors of soft materials as well as their dependence on molecular geometry, a series of AB n dendron-like molecules based on polyhedral oligomeric silsesquioxane (POSS) nanoparticles were designed and synthesized. The apex of these molecules is a hydrophilic POSS cage with 14 hydroxyl groups (denoted DPOSS). At its periphery, there are different numbers (n = 1-8) of hydrophobic POSS cages with seven isobutyl groups (denoted BPOSS), connected to the apical DPOSS via flexible dendron type linker(s). By varying the BPOSS number from one to seven, a supramolecular lattice formation sequence ranging from lamella (DPOSS-BPOSS), double gyroid (space group of Ia3̅d, DPOSS-BPOSS2), hexagonal cylinder (plane group of P6mm, DPOSS-BPOSS3), Frank-Kasper A15 (space group of Pm3̅n, DPOSS-BPOSS4, DPOSS-BPOSS5, and DPOSS-BPOSS6), to Frank-Kasper sigma (space group of P42/mnm, DPOSS-BPOSS7) phases can be observed. The nanostructure formations in thi...
Supramolecular organization of dendritic supermolecules into liquid crystalline mesophases
Comptes Rendus Chimie, 2009
In this manuscript, a complete and comprehensive study on main-chain liquid crystalline dendrimers is reported. In order to be able to finely tune, and thus control, the mesomorphism of such multicomponent supermolecules, various structural parameters were systematically modified, such as the core nature and connectivity, the degree and topology of branching, the molecular architecture, the generation, and the chain substitution pattern of the peripherally grafted pro-mesogenic groups. The increase of the molecular complexity and the effects of the structural manipulations proved to be very interesting for the design of multifunctional molecular materials, and provided new types of mesophases, enlarging as such the diversity of liquid crystalline supramolecular organizations. To cite this article: S. Buathong et al., C. R. Chimie 12 (2009).
Biomimetic self-templating supramolecular structures
In nature, helical macromolecules such as collagen, chitin and cellulose are critical to the morphogenesis and functionality of various hierarchically structured materials 1–3. During tissue formation, these chiral macromolecules are secreted and undergo self-templating assembly, a process whereby multiple kinetic factors influence the assembly of the incoming building blocks to produce non-equilibrium structures 1,4. A single macromolecule can form diverse functional structures when self-templated under different conditions. Collagen type I, for instance, forms transparent corneal tissues from orthogonally aligned nematic fibres 5 , distinctively coloured skin tissues from cholesteric phase fibre bundles 6,7 , and mineralized tissues from hierarchically organized fibres 8. Nature's self-templated materials surpass the functional and structural complexity achievable by current top-down and bottom-up fabrication methods 9–12. However, self-templating has not been thoroughly explored for engineering synthetic materials. Here we demonstrate the biomimetic, self-templating assembly of chiral colloidal particles (M13 phage) into functional materials. A single-step process produces long-range-ordered, supramolecular films showing multiple levels of hierarchical organization and helical twist. Three distinct supramolecular structures are created by this approach: nematic orthogonal twists, cholesteric helical ribbons and smectic helicolidal nanofilaments. Both chiral liquid crystalline phase transitions and competing interfacial forces at the interface are found to be critical factors in determining the morphology of the templated structures during assembly. The resulting materials show distinctive optical and photonic properties, functioning as chiral reflector/filters and structural colour matrices. In addition, M13 phages with genetically incorporated bio-active peptide ligands direct both soft and hard tissue growth in a hierarchically organized manner. Our assembly approach provides insight into the complexities of hierarchical assembly in nature and could be expanded to other chiral molecules to engineer sophisticated functional helical-twisted structures. As building blocks for the self-templating process we chose to use the bacterial virus M13 phage. Various viral particles have previously been used as model liquid crystal systems 13–16 and to create functional materials for nanoparticle synthesis and assembly 17,18 , for energy storage 19 and in tissue engineering 20,21. In particular, M13 was chosen for its helical, nanofibrous shape, for its monodispersity and for its ability to display multiple functional motifs (Fig. 1a). We then assembled the phage into large-area films by creating an apparatus to pull substrates vertically from phage suspensions at precisely controlled speeds (Supplementary Movie 1). As the substrates were pulled, evaporation proceeded fastest near the air–liquid–solid contact line resulting in the local accumulation and deposition of phage particles on the substrate at the meniscus (Fig. 1b). Two factors were critical to self-templating assembly. The first was the local induction of chiral liquid-crystal phase transitions at the meniscus; that is, twisted nematic (cholesteric) and chiral smectic structures (Supplementary
Frank–Kasper, quasicrystalline and related phases in liquid crystals
Soft Matter, 2005
The review covers 3-dimensional and some 2-dimensional self-assembly patterns of supramolecular liquid crystals possessing either quasi-periodic or closely related truly periodic order. Compounds showing such structures are amphiphilic, and most often wedge-shaped, with dendrons being the most common examples. The topology is described in terms of 3D and 2D tiling of a variety of polyhedra or polygons, respectively. Analogy is made with structures of metallic alloys and soap froth. The recently discovered dodecagonal liquid quasicrystal is compared with the different tetrahedrally close packed Frank-Kasper phases in thermotropic and lyotropic liquid crystals. Parallels are also drawn with honeycomb columnar phases with related plane tilings, including that of distorted pentagons. The potential for the creation of nearly isotropic photonic bandgap materials is mentioned.
Beyond liquid crystals: new research trends for mesogenic molecules in liquids
Journal of Materials Chemistry C, 2019
Looking to understand the supramolecular assemblies that bring together certain molecules to form innovative functional materials with high-potential applications, the present review focuses on recent examples of molecular structures that are susceptible of stablishing self-assemblies both in bulk and in solvents. This revision demonstrates that appropriate rod-and V-shaped, disc-like and star-shaped molecules as well as highmolecular-weight compounds, either dendrimers or polymers, exhibit a dual ability. Intermolecular interactions that provide liquid crystalline order in bulk may also manifest in solution and this allows to attain nanomaterials in the form of nanoaggregates. Through bottom-up approaches that involve the self-assembly of molecules driven by hydrogen bonding, π-π stacking, electrostatic or hydrophilic-hydrophobic interactions, appropriate molecules are able to induce a variety of thermotropic mesophases in bulk as well as aggregates with morphologies such as nanoparticles, nanofibers, nanorods or nanotubes in liquid media; including systems in which solvents are immobilized and form gel materials. The aim of this work is to highlight the versatility of mesogenic molecules, that in turn opens the door to a wide number of possibilities, and therefore to help this topic to enter into a more mature period.
Angewandte Chemie International Edition, 2019
Self‐assembled nanostructures of rod‐like molecules are commonly limited to nematic or layered smectic structures dominated by the parallel arrangement of the rod‐like components. Distinct self‐assembly behavior of four categories of dendritic rods constructed by placing a tri(hydroxy) group at the apex of dendritic oligo‐fluorenes is observed. Designed hydrogen bonding and dendritic architecture break the parallel arrangement of the rods, resulting in molecules with specific (fan‐like or cone‐like) shapes. While the fan‐shaped molecules tend to form hexagonal packing cylindrical phases, the cone‐shaped molecules could form spherical motifs to pack into various ordered structures, including the Frank–Kasper A15 phase and dodecagonal quasicrystal. This study provides a model system to engineer diverse supramolecular structures by rod‐like molecules and sheds new light into the mechanisms of the formation of unconventional spherical packing structures in soft matter.