Microsegregation in Liquid Crystalline Systems: Basic Concepts

Tschierske, Carsten

doi:10.1002/9783527671403.hlc074

Cited by 17 publications

(24 citation statements)

References 173 publications

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“…In general, different-shaped molecules, such as rods and disks, tend to exclude one another despite the large entropic penalty of the resulting phase separation (14). The combination of OCB Rod, a rod-shaped LC molecule affording a nematic order (Fig.…”

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confidence: 99%

Nematic-to-columnar mesophase transition by in situ supramolecular polymerization

Yano

Itoh

Araoka

et al. 2019

Science

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Disk- and rod-shaped molecules are incompatible in coassembly, as the former tend to stack one-dimensionally whereas the latter tend to align in parallel. Because this type of incompatibility can be more pronounced in condensed phases, different-shaped molecules generally exclude one another. We report that supramolecular polymerization of a disk-shaped chiral monomer in nematic liquid crystals comprising rod-shaped molecules results in order-increasing mesophase transition into a single mesophase with a core-shell columnar geometry. This liquid crystalline material responds quickly to an applied electric field, resulting in unidirectional columnar ordering. Moreover, it can be modularly customized to be optoelectrically responsive simply by using a photoisomerizable rod-shaped module. The modular strategy allows for cooperative integration of different functions into elaborate dynamic architectures.

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confidence: 99%

Nematic-to-columnar mesophase transition by in situ supramolecular polymerization

Yano

Itoh

Araoka

et al. 2019

Science

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“…Assuming that the influence of the spacers on the interaction energy between the mesogens is minor, the transition enthalpy Δ H mix should remain similar for all the compounds. At the clearing transition Δ H mix = T Cl Δ S mix . Consequently, with increasing spacer length the growing mixing entropy lowers the clearing temperature T Cl .…”

Section: Resultsmentioning

confidence: 98%

“…It has been suggested that the incommensurate packing distance of fullerenes (1.03 nm) and discotics (0.34 nm) were compensated by helical arrangements of the fullerene units. Similar to the star‐shaped mesogens SnFm , these liquid crystals can be described as shape amphiphiles, for which the driving force towards the helical assembly is the nanosegregation of fullerenes and the efficient space‐filling of the entire system. The stilbenoid scaffold has been chosen because it is shape‐persistent: the overall star topology remains, although different conformers can be realized by rotation about the single bonds between the phenyl groups and double bonds .…”

Section: Introductionmentioning

confidence: 96%

“…The precise control of the self‐assembly of different functional building blocks in soft materials is mastered by nature to create molecular machines and is the unequalled model for materials scientists. Without the help of the fully defined hydrogen bonding, the self‐assembly in liquid‐crystalline materials relies on nanosegregation of incompatible molecular units, their preorganization and flexibility, the efficient packing and space‐filling in the final structure . Recently, we reported a new concept for the formation of liquid crystals (LC) with more than one functional building block, in which stilbenoid scaffolds and chromophores such as fullerene or anthracene derivatives are double nanosegregated side‐by‐side in a single column .…”

Section: Introductionmentioning

confidence: 99%

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Fullerene‐Filled Stilbene Stars: The Balance between Isolated C₆₀ Helices and 3D Networks in Liquid‐Crystal Self‐Assemblies

Hügel

Dechant

Scheuring

et al. 2019

Chemistry A European J

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As eries of shape-persistent star-shapedo ligo(phenylene vinylene) liquid crystalsa nd derivatives with fullerene tethered through spacers of differentl engths to one arm were successfully synthesized.S olution studiesb yN MR, UV/ Vis and fluorescence spectroscopy revealed the preferential locationo ft he C 60 acceptori nt he vicinity of the peripheral donor unit, which affects the quenching of the emission of the conjugated stilbenoid scaffold in the donor-acceptor dyad. The fluorescencew as completely absenti nt he liquid crystal phase due to the extraordinary hierarchical self-assembly.I nt his family of mesogens, the intrinsic free space has to be filled either by an extremely tightp ackingo ft he stars or by the fullerenes as guests. Thes pacer lengths control the nanosegregation of the C 60 units in the cavities of the stars in either independent triplehelices or unprecedented 3D networks, in which fullerenes are positioned at the interfaceo fneighboringc olumns. Eventually,the clearing temperatureo fs uch large complex donor-acceptor systems can be tuned by an entropye ffect defined by the length of the spacer. Thea ccessibility of the isotropic phase without decomposition is an importantp rerequisite forf uture alignment studies associated with potentialm ateriala pplications in organic electronics.

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“…Enhanced mesophase stability is attributed to the segregation of the fluorinated segments from the non-fluorinated parts (RF), known to stabilize LC self-assembly [104][105][106]. This stronger segregation of RF compared to RH inhibits the mixing between lateral chains and the OPE rods, thus leaving only the possibility of lateral staggering of the OPE cores in the cylinder walls for reduction of the space in the triangular honeycombs (Figure 7c).…”

Section: Compmentioning

confidence: 99%

Effects of Lateral and Terminal Chains of X-Shaped Bolapolyphiles with Oligo(phenylene ethynylene) Cores on Self-Assembly Behaviour. Part 1: Transition between Amphiphilic and Polyphilic Self-Assembly in the Bulk

Poppe

Ebert

et al. 2017

Polymers

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Polyphilic self-assembly leads to compartmentalization of space and development of complex structures in soft matter on different length scales, reaching from the morphologies of block copolymers to the liquid crystalline (LC) phases of small molecules. Whereas block copolymers are known to form membranes and interact with phospholipid bilayers, liquid crystals have been less investigated in this respect. Here, series of bolapolyphilic X-shaped molecules were synthesized and investigated with respect to the effect of molecular structural parameters on the formation of LC phases (part 1), and on domain formation in phospholipid bilayer membranes (part 2). The investigated bolapolyphiles are based on a rod-like π-conjugated oligo(phenylene ethynylene) (OPE) core with two glycerol groups being either directly attached or separated by additional ethylene oxide (EO) units to both ends. The X-shape is provided by two lateral alkyl chains attached at opposite sides of the OPE core, being either linear, branched, or semiperfluorinated. In this report, the focus is on the transition from polyphilic (triphilic or tetraphilic) to binary amphiphilic self-assembly. Polyphilic self-assembly, i.e., segregation of all three or four incorporated units into separate nano-compartments, leads to the formation of hexagonal columnar LC phases, representing triangular honeycombs. A continuous transition from the well-defined triangular honeycomb structures to simple hexagonal columnar phases, dominated by the arrangement of polar columns on a hexagonal lattice in a mixed continuum formed by the lipophilic chains and the OPE rods, i.e., to amphiphilic self-assembly, was observed by reducing the length and volume of the lateral alkyl chains. A similar transition was found upon increasing the length of the EO units involved in the polar groups. If the lateral alkyl chains are enlarged or replaced by semiperfluorinated chains, then the segregation of lateral chains and rod-like cores is retained, even for enlarged polar groups, i.e., the transition from polyphilic to amphiphilic self-assembly is suppressed.

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Microsegregation in Liquid Crystalline Systems: Basic Concepts

Cited by 17 publications

References 173 publications

Nematic-to-columnar mesophase transition by in situ supramolecular polymerization

Nematic-to-columnar mesophase transition by in situ supramolecular polymerization

Fullerene‐Filled Stilbene Stars: The Balance between Isolated C₆₀ Helices and 3D Networks in Liquid‐Crystal Self‐Assemblies

Effects of Lateral and Terminal Chains of X-Shaped Bolapolyphiles with Oligo(phenylene ethynylene) Cores on Self-Assembly Behaviour. Part 1: Transition between Amphiphilic and Polyphilic Self-Assembly in the Bulk

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Microsegregation in Liquid Crystalline Systems: Basic Concepts

Cited by 17 publications

References 173 publications

Nematic-to-columnar mesophase transition by in situ supramolecular polymerization

Nematic-to-columnar mesophase transition by in situ supramolecular polymerization

Fullerene‐Filled Stilbene Stars: The Balance between Isolated C60 Helices and 3D Networks in Liquid‐Crystal Self‐Assemblies

Effects of Lateral and Terminal Chains of X-Shaped Bolapolyphiles with Oligo(phenylene ethynylene) Cores on Self-Assembly Behaviour. Part 1: Transition between Amphiphilic and Polyphilic Self-Assembly in the Bulk

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Fullerene‐Filled Stilbene Stars: The Balance between Isolated C₆₀ Helices and 3D Networks in Liquid‐Crystal Self‐Assemblies