Formation Of Lyotropic Liquid Crystals Research Articles

Stable graphene oxide-based lyotropic liquid crystals for interfacial lubrication

Lyotropic liquid crystals have lubricating properties due to their ordered assembly and fluidity, whose mesogens are often characterized by amphiphilic properties. Despite the attention that graphene oxide (GO) has been studied as a novel amphiphilic lyotropic mesogen this decade, and GO applied as a lubrication additive has been demonstrated in both oil and water-based systems, little research reveals the interfacial lubrication of GO liquid crystals yet. This work reports that GO aqueous dispersion can form lyotropic liquid crystals above a specific critical concentration of 5.00 mg/mL, providing a form of stable water-based lubricant, which can keep stable for several months and can reduce friction by 37.3% and wear by 25.24%. The liquid crystal phase was verified by polarizing microscope and synchrotron radiation small-angle X-ray scattering, and its rheological properties and viscoelasticity were studied by interfacial rheometer. The formation of lyotropic liquid crystals can enhance the stability of GO aqueous dispersions at high density, simultaneously ensuring friction decrease and anti-wear effect. It is attributed to the stable nematic network by the ordered GO sheets. The ordered assembly structure bears vertical shear force, therefore, reducing the wear. It is also assumed that the wide lateral size of graphene oxide promotes the nematic phase thus smoothes the graphene oxide film composed spontaneously under the coincidence of lamellar liquid crystal and 2D layered material. Through this work, the interlayer lubrication of GO was optimized, and the problem of GO dispersion sedimentation was solved by self-assembly. The range of interfacial lubrication of GO aqueous dispersion has been expanded and the synergistic effect is conducive to the environmentally friendly lubricants.

Bio-inspired liquid crystal gel induction via nano-hydroxyapatite mesogens: Viscoelastic and hemostasis regulation under bone remodeling pH and temperature control

In this work, a liquid crystal mesophase as a potential bone-repairing booster has been induced from a polyacrylic acid (PAAc) gel loaded with synthetic hydroxyapatite nanoparticles (nHA) under physiological conditions of pH and temperature that resemble the early stages of bone formation. Dynamic processes at the microscale in biological systems require a material capable of behaving following a specific order and fluency. Besides, they must fulfill conditions such as biocompatibility and good mechanical properties. Our study aimed to obtain new data about the safety, hemostasis, biocompatibility (activated partial thromboplastin time (APTT) test, prothrombin time (PT) test, lactate dehydrogenase (LDH) test, red blood cell morphology observation, hemolysis percentage) and physicochemical/mechanical behavior (Attenuated Total Reflection (ATR), Infrared spectroscopy and rheological assays) of nanoparticles, and materials built with them. Both systems have shown biocompatibility with red blood cells and adequate flow properties, demonstrating promising qualities for applicability. The formation of lyotropic liquid crystals at physiological conditions was evaluated with crossed polaroids microscope with a temperature control plate. The formation of these structures under bone remodeling conditions shows the potential application of PAAc-nHA materials. In literature, the study of materials applied as bone fillers is mainly focused on mechanical and osteoblasts compatibility assays. However, the hematological effect, consequences on the coagulation cascade, the integrity of cell membranes, and hemolysis percentage have not been addressed thoroughly. The strength of our work is focused on considering these aspects when tridimensional arrangements essential for bone formation are formed.

Ti3C2Tx MXene Liquid Crystal: Access to Create Background-Free and Easy-Made Alignment Medium.

The formation of lyotropic liquid crystals (LCs) in two-dimensional (2D) colloidal dispersions enables the production of mesoscopic/macroscopic ordered materials from nanoscale building blocks. In contrast to graphene oxide (GO) LCs, the practical applications of MXene LCs are less exploited. This study bridges the gap by utilizing a simple and versatile fabrication method to prepare Ti3C2Tx MXene LC that can be applied as a background-free alignment medium for the residual dipolar coupling (RDC) measurement of organic molecules. Ti3C2Tx LC displays the size- and concentration-dependent alignment degree. Ti3C2Tx nanoflakes with an average size of around 600 nm can provide the quadrupolar 2H splitting of 71 Hz at a concentration of 50 mg/mL and show excellent fluidity at such a high concentration. Compared with other alignment media, Ti3C2Tx LC exhibits the features of no-background and narrow line broadening, which actualizes the acquirement of clean and high-quality NMR spectra for the accurate RDC extraction. Notably, the alignment of LCs is determined to be maintainable in the redispersed solution after freeze-drying, providing the great convenience for the preparation of alignment Ti3C2Tx media, long-term sample preservation, and quantitative evaluation of alignment degree. Meanwhile, the alignment LC media for RDC measurement can be established in other MXenes such as Ti2CTx and Ti3CNTx. Collectively, our findings demonstrate the potential of creating various alignment media from the fascinating MXene family.

Synthesis and Characterization of Anatase TiO2 Nanorods: Insights from Nanorods’ Formation and Self-Assembly

Highly crystalline, organic-solvent-dispersible titanium dioxide (TiO2) nanorods (NRs) present promising chemicophysical properties in many diverse applications. In this paper, based on a modified procedure from literature, TiO2 NRs were synthesized via a ligand-assisted nonhydrolytic sol-gel route using oleic acid as the solvent, reagent, and ligand and titanium (IV) isopropoxide as the titanium precursor. This procedure produced monodisperse TiO2 NRs, as well as some semi-spherical titania nanocrystals (NCs) that could be removed by size-selective precipitation. X-ray diffraction and selected area electron diffraction results showed that the nanorods were anatase, while the semipheres also contained the TiO2(B) phase. By taking samples during the particle growth, it was found that the average length of the initially grown NRs decreased during the synthesis. Possible reasons for this unusual growth path, partially based on high-resolution transmission electron microscopy (HRTEM) observations during the growth, were discussed. The dispersion of anatase TiO2 nanorods was capable of spontaneous formation of lyotropic liquid crystals on the TEM grid and in bulk. Considering high colloidal stability together with the large optical birefringence displayed by these high refractive index liquid crystalline domains, we believe these TiO2 NRs dispersions are promising candidates for application in transparent and switchable optics.

Inducing Microscale Structural Order in Phage Nanofilament Hydrogels with Globular Proteins.

Biological hydrogels play important physiological roles in the body. These hydrogels often contain ordered subdomains that provide mechanical toughness and other tissue-specific functionality. Filamentous bacteriophages are nanofilaments with a high aspect ratio that can self-assemble into liquid crystalline domains that could be designed to mimic ordered biological hydrogels and can thus find applications in biomedical engineering. We have previously reported hydrogels of pure cross-linked liquid crystalline filamentous phage formed at very high concentrations exhibiting a tightly packed microstructure and high stiffness. In this work, we report a method for inducing self-assembly of filamentous phage into liquid crystalline hydrogels at concentrations that are several orders of magnitude below that of lyotropic liquid crystal formation, thus creating structural order but a less densely packed microstructure. Hybrid hydrogels of M13 phage and bovine serum albumin (0.25 w/v%) were formed and shown to adsorb up to 16× their weight in water. Neither component gelled on its own at the low concentrations used, suggesting synergistic action between the two components in the formation of the hydrogel. The hybrid hydrogels exhibited repetitive self-healing under physiological conditions and at room temperature, autofluorescence in three channels, and antibacterial activity toward Escherichia coli host cells. Furthermore, the hybrid hydrogels exhibited a more than 2× higher ability to pack water compared to BSA-only hydrogels and 2× lower compression modulus compared to tightly packed M13-only hydrogels, suggesting that our method could be used to create hydrogels with tunable mechanical properties and pore structure through the addition of globular proteins, while maintaining bioactivity and microscale structural order.

Geometric features in lyotropic liquid crystalline phase transitions observed in aqueous surfactant systems

Lyotropic liquid crystalline phases are widely known to be formed in aqueous surfactant mixtures. Although the phase behavior of several surfactants has been elucidated in the past years, a striking absence of detailed discussion on how molecular geometric parameters vary as different liquid crystals are formed is consistently seen in literature. The current work aimed to partially fill this gap, by determining how several structural parameters changed in a variety of phase transitions previously observed in aqueous surfactant binary and ternary mixtures. The main findings reveal that the cell parameter dimensions are strongly correlated with the packing fraction of small aggregates in each phase; the folding and interpenetration of surfactant hydrocarbon chains are most likely to happen in phases with lower curvature, and can greatly affect other structural parameters; added components can alter the aqueous surfactant phase behavior at different extents; and highly ordered phases are favored by a substantial decrease in the cross-sectional areas per surfactant; among others. The obtained results enable important knowledge on lyotropic liquid crystal formation, in addition to providing detailed information on how to control and obtain such phases, thus prospecting new insights in areas where they are highly desired.

Enhanced β-carotene encapsulation and protection in self-assembled lyotropic liquid crystal structures

The aim of this study was to form liquid crystalline structures for retaining and protecting β-carotene (β-c). Tween 40-Span 20 (TxSy) were blended for obtaining target hydrophilic-lipophilic balance (HLB) values ranging from 9 to 15. TxSy were mixed with canola oil (O) as carrier and water (W) as solvent and incubated for 10 days at 37 °C. The formation of lyotropic liquid crystals (LLC) was visually monitored. Pseudo-ternary phase diagrams were constructed to identify the region of LLC formation, which occurred only at HLB values of 11 and 12, the formation region being significantly larger in the former case. The experiments at HLB = 11 were repeated but substituting 0.7% of O by β-carotene (β-c) to produce LLC loaded with β-c (LLC β-c). Finally, LLC β-c were stored in darkness at 25 °C during five weeks. Best LLC β-c yield occurred for an O+β-c:TxSy:W ratio of 40:40:20 (p < 0.05), but the lowest degradation of β-c (17.26%) happened for an O+β-c:TxSy:W ratio of 36:54:10 (p < 0.05). This work provides a procedure for obtaining LLC systems for efficient protection, retention and/or release of nutraceuticals or bioactive compounds such as vitamins, antioxidants and smell substances, which may be used for developing novel food products with desired properties.

Dynamic Collapse Mechanism of Alveolar Type 1 Caveolae Buds Modeled as Cubic Mesophase Lyotropic Liquid Crystal Formation and Growth

The alveolar type 1 (AT1) cells cover 95% of the cell surface area while the alveolar type 2 cells cover the remaining 5% of 100–150 m2 surface area of the lung. AT1 maintain membrane integrity by surface tension via caveolin proteins that stretch and collapse the membrane bilayer in physiological pressure cycling, however, collapse mechanics of the AT1 membrane have not been elucidated. Golani et al. modeled globular caveolin collapse structure base on mean curvature and lateral tension, and other sources have constructed similar models. The parameters are transformations of the critical packing parameter CPP equals monomer dimensions predicts that the monolayer shape of surfactants, described as v/al. Deng et al. model for gemini surfactants at the air‐water interface and Turner et al. model for the formation of caveolae bulbs via energy displacement of a membrane bound proteins have proposed similar geometric theories that show resemblance to lyotropic liquid crystal swell equation. The models feature common mathematical properties which are 1) spherical geometry, 2) lattice parameter‐based expansion, and 3) monomer population as mechanical descriptors of bilayer transformation. Each model correlated positively with cubic formation and decrease in surface tension. Krianeva et al. showed that monolayer of monoolein formed a new phase of bicontinuous phase, P4332, as the concentration of protein Horse cytochrome c increased. The spherical formation models predicted mesophases are cubic meaning that they are CPP &gt;&gt; 1, micellar cubic shape. The overall result, the caveolin bud shape is cubic bicontinuous mesophase, which is stabilized under physiological pressure cycling in the AT1 cell. We propose, the caveolin bud shape is a cubic bicontinuous mesophase stabilized under physiological pressure cycling in AT1 cell membrane and mechanics can be modeled by using the lamellar to cubic transition or the swelling law using change in surface tension vs lattice parameter as the formation rate. Furthermore, caveolin and cavin proteins present during the time of formation induce invagination, and, second, stabilization and fragility. Agarwal et al. show the transition phase between isotropic and cubic mesophase is a volume fraction difference of 0.05, a metastable polyhedral lattice produced by caveolin proteins, characterizing bud formation as plastic liquid crystal phase transition. This model could explain mechanoprotection by caveolae bud, and gives us a platform to think about self‐assembling monomer‐based medicines when approaching physical stretch dysfunction repair in the lung.Equations are models that describe cubic expansion from the lamellar setting across several membrane simulations. Equation 1 (left) describes the radius, r1, of Gemini surfactant. Equation 2 (middle) describes the formation of caveolae bulbs via the energy displacement of membrane‐bound proteins. Equation 3 (left) describes the swelling law of lyotropic mesophases.Figure 1

Synthesis of Platinum-Containing Conjugated Polymers Having QuinoxP* and Bipyridine Ligands. Chirality Transfer from the Phosphine Ligand to the Polymer Backbone

Platinum (Pt)-containing novel conjugated polymers, poly­(1-2a)–poly­(1-2d) having bipyridine ligands were synthesized by the Sonogashira–Hagihara coupling polymerization of [Pt­(4,4′-dibromo-2,2′-bipyridine)­((R,R)-2,3-bis­(tert-butylmethylphosphino)­quinoxaline)­(trifluoromethanesulfonate)2] (1) coordinated with 4,4′-dibromo-2,2′-bipyridine/(R,R)-2,3-bis­(tert-butylmethylphosphino)­quinoxaline [(R,R)-QuinoxP*] and 1,4-diethynylbenzene (2a), 1,4-diethynyl-2,5-bis­(heptyloxy)­benzene (2b), 1,4-diethynyl-2,5-bis­(2-ethylhexyloxy)­benzene (2c), and 1,4-diethynyl-2,5-bis­(2-(2-methoxyethoxy)­ethoxy)­benzene (2d). Poly­(1-2d) exhibited circular dichroism signals derived from (R,R)-QuinoxP* and the conjugated main chain around 290 and 440 nm in DMF, respectively. The simulated CD spectroscopic pattern of a low molecular model compound, M1-Pt, agreed well with the observed spectra. The TEM images of poly­(1-2d) in the solid state exhibited dispersed patterns with sizes around 10 nm. Concentrated solutions of polymer 1-2d in DMF and CHCl3 partly exhibited patterns assignable to the formation of lyotropic liquid crystals.

Columnar Liquid Crystals Self-Assembled by Minimalistic Peptides for Chiral Sensing and Synthesis of Ordered Mesoporous Silica

We report the spontaneous formation of lyotropic liquid crystals from the self-assembly of a series of minimalistic peptides. The highly charged peptides could self-assemble into rigid helical nanofilaments in water and spontaneously order into hexagonal liquid-crystalline phases with interfilament separations of ≤240 A. The formation of liquid crystals from the self-assembly of such simple peptides is dictated not only by the concentration and pH but also by the amino acid sequence of the peptides. Peptides containing the rigid Phe-Phe (FF) segment showed much higher propensities to form a liquid-crystalline phase with long-range order. Moreover, because of the intrinsic chirality of the peptides, the self-assembled birefringent liquid crystals could serve as sensing elements for the visual discrimination of chiral species and as templates for the biomimetic synthesis of mesoporous silica with ordered cavities. The results offer new opportunities for the design of peptide liquid crystals that are potenti...

Effect of hydrogen bonding on the liquid crystalline behavior of Poly(p-phenylene terephthamide) in sulfuric acid

Many factors affect the formation of lyotropic liquid crystals (LLCs) in the poly(p-phenylene terephthamide) (PPTA)/H2SO4 system. In this systematic work, we prove that the hydrogen bonding between PPTA and H2SO4 plays a very important role for the LLC formation by using a combination of several characterization methods. Texture features and transition temperatures of different phases owing to hydrogen bonding in the PPTA/H2SO4 system were obtained by using polarized light microscopy and differential scanning calorimetry. 13C NMR and FTIR spectroscopy were applied to investigate the chemical structures in different phases, especially the hydrogen bonding between PPTA and H2SO4. The effect of molecular weight on phase transition was also examined. Moreover, guest compounds such as H2O, CH3SO3H, and carbon nanotube added will destroy the hydrogen-bonding network in the PPTA/H2SO4 system, resulting in different phase behaviors. All these results demonstrate that hydrogen bonding between PPTA and H2SO4 is the key factor for the highly ordered arrangement of polymer chains in the LLC state that is a nematic phase.

Competition brings out the best: modelling the frustration between curvature energy and chain stretching energy of lyotropic liquid crystals in bicontinuous cubic phases.

It is commonly considered that the frustration between the curvature energy and the chain stretching energy plays an important role in the formation of lyotropic liquid crystals in bicontinuous cubic phases. Theoretic and numeric calculations were performed for two extreme cases: parallel surfaces eliminate the variance of the chain length; constant mean curvature surfaces eliminate the variance of the mean curvature. We have implemented a model with Brakke's Surface Evolver which allows a competition between the two variances. The result shows a compromise of the two limiting geometries. With data from real systems, we are able to recover the gyroid-diamond-primitive phase sequence which was observed in experiments.

Lyotropic liquid crystal behavior of carboxylated cellulose nanocrystals

In this work, the lyotropic liquid crystal (LC) behavior of carboxylated cellulose nanocrystals (CNs) has been studied for cotton cellulose prepared by TEMPO-mediated oxidation of cellulose nanocrystals (TOCNs). It is found that suspensions of TOCNs at a critical concentration of 4.1wt% form anisotropic phase with clear optical birefringence. Furthermore, fingerprint texture is clearly observed when the concentration is 9.0wt% under a polarizing optical microscope. Fingerprint texture is characteristic of chiral nematic liquid crystal (N*-LC) phase. The band-spacing corresponds to half the helical pitch, and thus, the helical pitch of N*-LCs (9.0wt%) is about 6.0μm. The degree of oxidation (DO) and zeta potential of TOCNs in suspension are 0.15 and −59.5mV, respectively. Relatively larger aspect ratio and higher surface charges density of TOCNs make the critical concentration of LC formation decreased and the helical pitch increased compared to that of the LC prepared by H2SO4 hydrolysis system. The interparticle electrostatic repulsion between CNs with different surface charges influence the helical pitch of N*-LCs.

Well-Defined Polymer-Brush-Coated Rod-Shaped Particles: Synthesis and Formation of Liquid Crystals

The surface of hematite rods (α-Fe2O3 rods; aspect ratio = 6, semimajor axis = 600 nm) was modified by surface-initiated atom transfer radical polymerization (SI-ATRP). The copper-catalyzed SI-ATRP of methyl methacrylate (MMA) was conducted on the surface of the initiator-fixed α-Fe2O3 rods using a free (sacrificial) initiator, ethyl 2-bromoisobutyrate. Well-defined poly(MMA) (PMMA) brushes were densely grafted on the rods with a chain density of up to 0.7 chains/nm2. These hybrids composed of a rod-shaped particle as the core and a PMMA brush as the shell were highly dispersed in any of “good solvents” for PMMA. Double-layer (organic layer/inorganic layer)-coated α-Fe2O3 rods were also fabricated by grafting PMMA brushes on the surface of silica-coated α-Fe2O3 rods. The α-Fe2O3 cores of the hybrid rods were etched with hydrochloric acid, affording hollow hybrid rods. Polarized optical microscopy confirmed the formation of lyotropic liquid crystals by the rods grafted with polymer chains of a proper length.

Lyotropic liquid crystals fabricated in ionic liquids

The lyotropic liquid crystals (LLCs) are one important kind of aggregates formed by surfactants in solvent media and have wide applications in nanomaterial systhesis, chemical reaction environment, drug delivery, lubricating material, oil recovery and so on. Meanwhile, the ionic liquids (ILs) have currently widely used as novel nonaqueous media in the areas of organic synthesis and catalysis, biochemical engineering, materials science, electrochemistry, carbohydrate chemistry, and separation techniques for their unique characteristics of low melting temperature, negligible vapor pressure, wide electrochemical window, nonflammability, good catalytic properties, high thermal stability, and ionic conductivity. For these reasons, more and more attention has been paid to ILs as the self-assembly media. Among them, the LLCs formed by surfactants in ILs have received increasingly studies. Exploration on the LLC behaviors of surfactants in ILs may provide not only a better understanding of intermolecular actions in self-assembly, but also certain new properties to LLCs, like better thermostability compared to those constructed in aqueous media. For these reasons, this account here reviews the LLC phase behaviors in ILs of various surfactants, including quarternary ammonium cationic surfactant, alkyl polyoxyethylene nonionic surfactant and Pluronic block copolymer. For the cationic surfactants, several single chain molecules like the hexadecyltrimethylammonium bromide, 1-hexadecyl-3-methylimidazolium chloride, and N-hexadecyl-N-methylpyrrolidinium bromide, their phase behaviors in various ILs were summaried. Various LLC phases including the normal hexagonal, lamellar, and reverse bicontinuous cubic LLC phases could be detected in ethylammonium nitrate (EAN). The hexagonal LLC phase with better thermostability was formed in EAN compared to that in water. For the molecule with two alkyl chains on one head, the dimethyldidodecylammonium bromide, the sponge and lamellar phases were observed in EAN and the sponge phase could be extended to larger region than that in aqueous system. Unlike the single chain surfactants, the reverse hexagonal phases were observed in the quarternary ammonium Gemini surfactants/EAN systems, which were not observed in corresponding water media. With increasing the chain length of one or two ethylene groups in cation of EAN, that is, from EAN to PAN or BAN, the normal LLC phases were formed back. As for the polyoxyethylene nonionic surfactants (C n E m ) in EAN, their phase behaviors were similar to those in water. Due to the weaker solvophobic interactions in EAN than in water, the longer alkyl chains were necessary for the formation of LLC. While in aprotic ILs, no LLC phase was observed. However, for the phytosterol ethoxylate surfactants (BPS-n), the LLC phases were observed both in EAN and also in aprotic ILs like [Bmim]BF4 and [Bmim]BF6. Similar aggregation behaviors were also observed for Pluronic block copolymer in EAN and [Bmim]BF4. The difference in phase behaviors of these surfactants in various ILs was analyzed by Gordon parameter, which was a measure of the cohesive energy density of the solvent. Generally speaking, ILs with higher Gordon parameters are correspondent to greater LLC diversity and better thermostability. The protic ionic liquids, which are capable of accepting protons and form hydrogen bonding network, would have a stronger ability of supporting surfactant self-assembly than the aprotic ionic liquids. This is the reason why richer phases are usually formed in EAN than in [Bmim]BF4 and [Bmim]BF6. Based on the review, the perspective for future research in this area has been also provided, such as synthesis of novel kinds of ILs and surfactants and investigation on new self-assembly systems.

Unique Phase Behaviors in the Gemini Surfactant/EAN Binary System: The Role of the Hydroxyl Group.

The hydroxyl group in the spacer of a cationic Gemini surfactant (12-3OH-12) caused dramatic changes of the phase behaviors in a protic ionic liquid (EAN). Here, the effects of the hydroxyl group on micellization and lyotropic liquid crystal formation were investigated through the surface tension, small-angle X-ray scattering, polarized optical microscopy, and rheological measurements. With the hydroxyl group in the spacer, the critical micellization concentration of 12-3OH-12 was found to be lower than that of the homologue without hydroxyl (12-3-12) and the 12-3OH-12 molecules packed more densely at the air/EAN interface. It was then interesting to observe a coexistence of two separated phases at wide concentration and temperature ranges in this 12-3OH-12/EAN system. Such a micellar phase separation was rarely observed in the ionic surfactant binary system. With the increase of surfactant concentration, the reverse hexagonal and bicontinuous cubic phases appeared in sequence, whereas only a reverse hexagonal phase was found in 12-3-12/EAN system. But, the hexagonal phases formed with 12-3OH-12 exhibited lower viscoelasticity and thermostability than those observed in 12-3-12/EAN system. Such unique changes in phase behaviors of 12-3OH-12 were ascribed to their enhanced solvophilic interactions of 12-3OH-12 and relatively weak solvophobic interactions in EAN.

Ternary phase behavior of phytosterol ethoxylate, water, and imidazolium-based ionic liquid systems – Lyotropic liquid crystal formation over a wide range of compositions

Abstract Lyotropic liquid crystal formation from ternary mixtures of nonionic surfactants [phytosterol ethoxylates (BPS-n)], water, and room-temperature ionic liquids [1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6) and 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4)] was evaluated using optical and polarized microscopic observations, small-angle X-ray scattering (SAXS), and rheological measurements. In this study, the number of POE units was varied (BPS-n, n = 10, 20, 30) to form lyotropic liquid crystalline phases over a wide composition range for all of the systems. The major liquid crystalline phases formed for BPS-10, -20, and -30 were lamellar, hexagonal, and cubic phases, respectively. The differences could be explained by the size of the hydrophilic moieties (i.e., a decrease in critical packing parameters through an increase in the number of surfactant POE units). In addition, structural parameters were calculated from SAXS data for the hexagonal liquid crystalline phase with 60 wt% BPS-20. The area occupied by the hydrophilic moieties in the hexagonally packed cylinder micelle decreased with increasing ratio of water to ionic liquid, which indicated that the surfactant molecules were packed more closely in the hexagonal liquid crystalline phase at greater water concentrations. Rheology measurements indicated that ternary mixtures exhibited more elastic behavior at greater water concentrations, which also supports the change in structural parameters suggested by SAXS measurements.

Lyotropic Supramolecular Helical Columnar Phases Formed byC3-Symmetric and Unsymmetric Rigid Molecules

Unlike thermotropic liquid-crystalline C(3)-symmetric molecules with flexible chains, the herein-designed fully rigid three-armed molecules (C(3)-symmetric and unsymmetric) create a fancy architecture for the formation of lyotropic liquid crystals in water. First, hollow columns with triple-stranded helices, analogous to helical rosette nanotubes, are spontaneously constructed by self-organization of the rigid three-armed molecules. Then, the helical nanotubes arrange into hexagonal liquid-crystalline phases, which show macroscopic chirality as a result of supramolecular chiral symmetry breaking. Interestingly, the helical nanotubes constructed by the fully rigid molecules are robust and stable over a wide concentration range in water. They are hardly affected by ionic defects at the molecular periphery, that is, further decoration of functional groups on the molecular arms can presumably be realized without changing the helical conformation. In addition, the formed columnar phases can be aligned macroscopically by simple shear and show anisotropic ionic conductivity, which suggests promising applications for low-dimensional ion-conductive materials.

Self-Assembly of Double-Tail Anionic Surfactant Having Cyanobiphenyl Terminal Groups in Water

This study reports the interfacial properties and lyotropic liquid crystal formation of sodium 1,2-bis{6-[4-(4-cyanophenyl)phenyloxy]hexyloxycarbonyl}ethanesulfonate (SBCPHS), which is a double-tail surfactant with cyanobiphenyl terminal groups, in water. Polarized microscopic observation of water/SBCPHS mixtures revealed the presence of columnar and lamellar phases. In the lamellar phase, myelin figures representing multilamellar tubes were observed, and some of these figures had a double-helix structure. In order to examine these liquid crystal structures in detail, the bilayer thickness of the lamellar tubes and the lattice parameters of the columnar phase were measured by small-angle X-ray scattering analysis. Four scattering peaks that could be ascribed to C2/m symmetry were observed for the columnar phase. The bilayer thickness and one of the lattice parameters were smaller than twice the molecular length of SBCPHS; this showed that the liquid crystal phases had intercalated structures. Comparison of SBCPHS with a typical double-tail hydrocarbon surfactant revealed that the cyanobiphenyl terminal groups in the former helped increase the stability of the liquid crystal formed at low temperatures. The stabilizing effect of the cyanobiphenyl terminal groups on the liquid crystals could have been driven by electrostatic intermolecular interactions between the terminal groups in antiparallel arrangement of the SBCPHS molecules.

Formation of Lyotropic Liquid Crystals from a Fatty Acid and a Nitrogenous Heterocyclic Compound in Water

Abstract Lyotropic liquid crystalline (LLC) phases of lauric acid in water have been successfully constructed with the aid of a N-heterocyclic compound in water. This novel ternary system can exhibit Lα phase with its lamellar spacing changing regularly in a wide concentration range.