Helical Nanofilament Phases

Hough, Loren E.; Jung, Hee‐Tae; Krüerke, Daniel; Heberling, Michael‐Scott; Nakata, Michi; Jones, Christopher D.; Chen, D.; Link, Darren R.; Zasadzinski, Joseph A.; Heppke, G.; Rabe, Jürgen P.; Stocker, W.; Körblová, Eva; Walba, David M.; Glaser, Matthew A.; Clark, Noel A.

doi:10.1126/science.1170027

Cited by 300 publications

(458 citation statements)

References 23 publications

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“…No other periodicity up to 15 nm length scales can be found. The correlation length x ¼ 2/Dq ¼ 21 nm corresponding to a domain size wB2, xB40 nm (Francescangeli et al 20 ), is in accordance with the typical width of the helical nanofilaments found by FFTEM 6 . Polarizing optical microscopy textures of 5-10 mm films are grainy dark blue indicating low birefringence in the B4 phase.…”

Section: Resultssupporting

confidence: 57%

“…2a) that varies in the short range 100-120 nm from one homologue to another. The period h of the families of fringes equals half pitch of the nanofilaments found in FFTEM experiments by Hough et al 6 , indicating that the filaments in Fig. 2 grow parallel to the substrate.…”

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

“…Remarkably, the B7 and B4 structures are helical in the micrometre 5 or nanometre 6 ranges, respectively. Freeze-fracture transmission electron microscopy (FFTEM) studies of the B4 phase revealed an assembly of twisted layers stacked to form chiral nanobundles with around wB40 nm widths and hB100 nm half pitch 6 . This helical nanofilament (HNF) phase is particularly interesting owing to its unique hierarchical nanostructure 7,8 in which the individual filaments further selforganize into oriented arrays of filaments that are phase coherent with respect to their twist.…”

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Helical nanofilaments of bent-core liquid crystals with a second twist

et al. 2014

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The B4 phase of bent-core liquid crystals has been shown to be an assembly of twisted layers stacked to form helical nanofilaments. Interestingly, some of them have structural colours that cannot be explained by the nanofilaments alone. Here cryogenic-transmission electron microscopy observations on 40-120 nm films of four bent-core liquid crystal materials show that the filaments are present even in contact with a carbon substrate with only minor deformation, thus representing bulk properties. We find that the subsequent arrays of nanofilaments are not parallel to each other, but rotate by an angle of 35-40°with respect to each other. This doubly twisted structure can explain the structural colour. Being principally different from the packing of molecules in the twist grain boundary and blue phases, the double-twist structure of helical nanofilaments expands the rich word of nanostructured organic materials.

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Section: Resultssupporting

confidence: 57%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Helical nanofilaments of bent-core liquid crystals with a second twist

et al. 2014

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“…The chirality of fd wt rods is left handed 26,27 , which imposes a well-defined handedness onto the colloidal membrane edge. This complex edge behaviour is one specific manifestation of a very general packing frustration present whenever chiral molecules are forced to assemble into 2D smectic-like sheets [28][29][30][31] .…”

Section: Resultsmentioning

confidence: 99%

Imprintable membranes from incomplete chiral coalescence

et al. 2014

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Coalescence is an essential phenomenon that governs the equilibrium behaviour in a variety of systems from intercellular transport to planetary formation. In this report, we study coalescence pathways of circularly shaped two-dimensional colloidal membranes, which are one rod-length-thick liquid-like monolayers of aligned rods. The chirality of the constituent rods leads to three atypical coalescence pathways that are not found in other simple or complex fluids. In particular, we characterize two pathways that do not proceed to completion but instead produce partially joined membranes connected by line defects-p-wall defects or alternating arrays of twisted bridges and pores. We elucidate the structure and energetics of these defects and ascribe their stability to a geometrical frustration inherently present in chiral colloidal membranes. Furthermore, we induce the coalescence process with optical forces, leading to a robust on-demand method for imprinting networks of channels and pores into colloidal membranes.

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Liquid Crystals

Bisoyi

2014

Kirk-Othmer Encyclopedia of Chemical Technology

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Liquid crystals (LCs) represent a state of matter which is characterized by a unique combination of order and mobility on molecular, supramolecular and macroscopic levels. This is a true thermodynamic stable state of matter and has been recognized and accepted as the fourth state of matter after solid, liquid, and gas (1-18). They have developed from a mere scientific curiosity in the beginning to one of the foundations of mobile information technology devices today (19)(20)(21)(22)(23)(24)(25). LCs are presently common topics in academic books and also in our daily life. Terms such as LCD, ie, LC display, and Kevlar have become familiar consumer products. The unusual feature which makes this state of matter unique among the others is the combination of orientational (and, sometimes, positional) order and dynamics, giving rise to materials with anisotropic physical properties that are switchable under the influence of small external stimuli. LCs have been regarded as unique functional soft materials from both scientific and technological point of view. The unique combination of counterintuitive properties, ie, order and fluidity, is not only an essential requirement for living matter, but also it is the foundation of the numerous technological applications of LC materials. Simultaneous exhibition of order and dynamics is the basic principle for self-organization and structure formation in living systems. Accordingly, LCs play a crucial role in living systems and in biology (18). For example, no life would be possible without the ordered and dynamic self-assembly of lipids into bilayers within the cell membrane. Several biological molecules such as lipids, carbohydrates, proteins, and nucleic acids have been found to exist in various liquid crystalline phases (26-34). The appearance of mesomorphism in DNAs has been related to the significant role that LCs would have played in the evolution of biological information in the pre-biotic world (35-38). LCs self-assemble into various structures with the help of many different types of molecular interactions such as van der Waals, dipolar and quadrupolar interaction, charge transfer, p-p interaction, metal coordination, and hydrogen bonding. Thus, LCs can be considered as prototype supramolecular systems which furnish well-defined self-assembled architectures using noncovalent secondary interactions (39). Scientifically, the LC field is a fertile ground to study supramolecular self-assembly of matter and soft materials. Moreover, LCs persuasively demonstrate the powerful organization principle of matter by maximizing the interaction energy and minimizing the excluded volume.Overall, LCs have developed into a fascinating and prosperous field, reaching out into different areas of science by providing basic knowledge of the fundamental rules governing self-assembly from simple to complex modes. The domains of LCs span across multiple disciplines of pure and applied science including optics, materials science, bioscience, nanoscience etc. Their science and technology are tru...

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Helical Nanofilament Phases

Cited by 300 publications

References 23 publications

Helical nanofilaments of bent-core liquid crystals with a second twist

Helical nanofilaments of bent-core liquid crystals with a second twist

Imprintable membranes from incomplete chiral coalescence

Liquid Crystals

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