Mesophase Structure Research Articles

Beyond the boundaries of organics biosorption: Reusable and cost-effective millet-straw-based carboxylate-functionalized mesoporous MCM-41

In this study, we prepared highly porous citric acid-functionalized mesoporous MCM-41 (C-MCM-41) molecular sieve adsorbent from millet straw agricultural residue, which was used for the effective remediation of wastewater contaminated with methylene blue (MB) and ciprofloxacin (CIP). The two-step synthesis process involved extracting highly pure silica from millet straw as a precursor for the ordered mesoporous silica MCM-41. The MCM-41 was synthesized via surfactant-mediated pore design before calcination, followed by citric acid grafting to improve surface functionality and enhance adsorption efficiency. Characterization techniques including XRD, SEM, HRTEM, FTIR, and zeta potential analysis confirmed the mesophase structure, honeycomb pore architecture, functional groups incorporation, and a more electronegative surface, respectively, due to the incorporated carboxyl moieties. Nitrogen adsorption-desorption studies showed a high surface area, which reduced slightly after functionalization. Adsorption of MB and CIP on the C-MCM-41 was superior to the unmodified MCM-41, and the Langmuir isotherm and pseudo-second-order models fitted the equilibrium and kinetic data, respectively. Reuse and cost analysis revealed that C-MCM-41 maintained over 90 % efficiency after four adsorption-desorption cycles and offers a sustainable and cost-effective alternative to conventional adsorbents, demonstrating higher efficiency in treating real wastewater. SynopsisSustainable and cost-effective silica was sourced from biomass and employed for the synthesis of reusable citric acid-functionalized ordered mesoporous silica which was used for the effective treatment of antibiotics contaminated wastewater

Lyotropic liquid crystal emulsions of LAVR-289: Influence of internal mesophase structure on cytotoxicity and in-vitro antiviral activity

Emerging and reemerging viruses pose significant public health threats, underscoring the urgent need for new antiviral drugs. Recently, a novel family of antiviral acyclic nucleoside phosphonates (ANP) composed of a 4-(2,4-diaminopyrimidin-6-yl)oxy-but-2-enyl phosphonic acid skeleton (O-DAPy nucleobase) has shown promise. Among these, LAVR-289 stands out for its potent inhibitory effects against various DNA viruses. Despite its efficacy, LAVR-289s poor water solubility hampers effective drug delivery. To address this, innovative delivery systems utilizing lipidic derivatives have been explored for various administration routes. Submicron lyotropic liquid crystals (LLCs) are particularly promising drug carriers for the encapsulation, protection, and delivery of lipophilic drugs like LAVR-289.This study focuses on developing submicron-sized lipid mesophase dispersions, including emulsified L2 phase, cubosomes, and hexosomes, by adjusting lipidic compounds such as Dimodan® U/J, Lecithins E80, and Miglyol® 812 N. These formulations aim to enhance the solubility and bioavailability of LAVR-289. In vitro evaluations demonstrated that LAVR-289-loaded LLCs at a concentration of 1 µM efficiently inhibited vaccinia virus in infected human cells, with no observed cytotoxicity. Notably, hexosomes exhibited the most favorable antiviral outcomes, suggesting that the internal mesophase structure plays a critical role in optimizing the therapeutic efficacy of this drug class.

Polymer dispersed cholesteric liquid crystals with combined photo- and mechanochromic response

The development of stimuli-sensitive systems is one of the newest and most promising directions in the field of modern materials science. The combination of various types of sensitivity in the same material opens the possibility of creating complex devices with a wide range of potential applications. This work deals with the design and preparation of new composite materials based on plasticized polyvinyl alcohol (PVA) films containing droplets of cholesteric liquid crystals (CLC). Mechanical stretching of elastic composite films results in a change in optical properties, namely selective light reflection (SLR), from CLC droplets. This in turn transforms the structure and optical properties of the entire polymer matrix. Such a process represents a certain mechano-optic response of the polymer matrix to the influence of mechanical deformation. The introduction of a chiral photochromic dopant into a composite film makes it possible to transform such a film into a photochromic material with the ability to control its optical properties using, for example, UV irradiation. Therefore, mechanical deformation of a polymer composite leads to a change in its optical properties (SLR) caused by a change chiral supramolecular structure of cholesteric mesophase. At the same time, UV irradiation of a polymer film induces E-Z isomerization process in the chiral photochromic dopant, altering its molecular shape and helical twisting power. This enables the using of this process for remote and contactless control of the composite optical properties. In addition, this feature allows one to implement the photopatterning and the recording of a latent image, which appears under the influence of a mechanical field.

Effect of thermal activation on the phase composition, microstructure and cementing performance of 5Mg(OH)2·MgSO4·7H2O

To reduce carbon dioxide emissions, environmental pressure caused by the magnesium oxysulfate (MOS) cement production process or the expiration of service life must be avoided. This experiment investigated the changes in the phase structure and microstructure of the 517 phase (5 Mg(OH)2·MgSO4·7H2O) after medium- or high-temperature treatment and its performance after remixing with water. The results were characterized by X-ray diffraction (XRD), thermal gravity-differential thermal gravity (TG-DTG), and scanning electron microscopy (SEM). The results show that the 517 phase can be dehydrated to form a mesophase after medium-temperature treatment, and these mesophase structures decompose with increasing treatment time. These mesophase products have cementing properties, and the 517 phase can be reformed by mixing the mesophase with water and has a certain strength. The raw material of MOS cement obtained from 517 treated at 500 °C has high activity, so a retarder is needed to reform the 517 phase. The modified sample has higher mechanical properties, which can meet the application needs.

Mechanical properties of isotactic polypropylene with nodular or spherulite morphologies

Abstractα‐form crystalline isotactic polypropylene (PP) was prepared by two methods: quenching from the melt state at slow or high crystallization rates. The mechanical properties of the resulting PP samples were evaluated using tensile and stress–relaxation tests to investigate the influence of nodular or spherulite morphologies. PP samples with different morphologies had almost the same crystallinity after annealing at 100°C for 5 h. The yielding stress, strain‐hardening modulus, and strength of the nodular PP were higher than those of the spherulite PP, although the crystallinity was almost the same for both PP samples. Furthermore, the relaxation time during the stress–relaxation process at ε = 4.0 was longer for the nodular PP than for the spherulite PP. The lamellar structure of a spherulite morphology comprises parent and daughter lamellar crystals, whereas that of a nodular morphology prepared via a mesophase structure comprises only parent lamellar crystals. The formation of the daughter lamellae reduces the number of tie chains. Therefore, the nodular PP has more tie chains than the spherulite PP. This transformation from a spherulite to a nodular morphology improved the mechanical properties of the PP.Highlights Influences of morphology on mechanical properties of polypropylene (PP). Tensile properties were higher for nodular PP than spherulite PP. Relaxation time of nodular PP was longer than spherulite PP. Nodular PP has more tie chains, resulting in improvements of tensile properties.

The effect of n-heptane soluble content on the composition and structure of coal tar pitch and the preparation of needle coke

To explore the effect of n-heptane soluble (HS) content in refined coal tar pitch (RCTP) on the preparation of needle coke (NC), a series of RCTP with different HS content were prepared by the solvent method. The RCTPs were reacted at 490 °C and 0.2 MPa for 6 h to obtain green cokes (GCs), and the GCs were calcined at 1400 °C to obtain NCs. The properties of RCTPs were studied by Fourier transform infrared (FTIR) spectroscopy, 1H nuclear magnetic resonance spectrum (1H NMR), and thermogravimetric (TG) analyses. The appearance and polarized microstructure of the GCs, and the Scanning electron microscope (SEM) image, X-ray diffraction (XRD) spectroscopy, Raman spectroscopy, linear expansion coefficient, and true density of the NCs were obtained and analyzed. The results show that with the decrease of HS content, the aromaticity of RCTPs increases, and the amount and length of branched chains decrease. Mesophase structures in GCs formed by these RCTPs have different types and orientations, which leads to obvious quality differences in NCs. The NC prepared from RCTP with HS content of 15.9% (RCTP-4) has the lowest linear expansion coefficient of 0.991 × 10−6 /°C, the highest true density of 2.1195 g/cm3, better fiber structure and carbon microcrystalline structure. Therefore, the HS content should be controlled not less than 15.9%, and the TI content should not be higher than 12.6% when RCTP was prepared by solvent method.

Novel antiferroelectric materials with resorcinol-based symmetrical fluorinated bent-core mesogens

The synthesis of several symmetrical bent-core compounds with two or four fluorine atoms as substituents on the calamitic units is reported. The influence of fluorine substitution concerning its effect upon the mesophase structure and switching behavior was investigated. The synthesized compounds are built from resorcinol as central core and contain seven phenyl rings linked by ester, imine and azo units with terminal decyloxy/dodecyloxy chains. The mesophases were characterized by polarizing optical microscopy, differential scanning calorimetry, electro-optical investigations and X-ray diffraction (XRD) studies. The photochemical characterisation of bent-core azobenzene compounds confirmed the structure of E isomer. The temperature range of mesophases increases upon the introduction of fluorine substituents, as compared with the corresponding unsubstituted compound. All the compounds exhibit antiferroelectric properties. Depending on the number of the F substituents, racemic SmCSPA mixtures and SmCAPA homochiral structures were identified. High values of spontaneous polarization up to 900 nC/cm2 were recorded. DFT studies were used to calculate the minimum energy molecular structures, the dipole moments and the electrostatic potential surfaces of the compounds.

Morphological transformation of extruded isotactic polypropylene film from the Mesophase to α-form crystals

The morphological transformation of extruded polypropylene (PP) films from the mesophase to α-form crystals has been investigated. Extruded PP films prepared by quenching had the mesophase morphology with a nearly-random orientation of the molecular chains. The mesophase structure of the quenched PP films completely transformed to α-form crystals by annealing at 100 °C accompanied by enhancement of the molecular orientation along the machining direction (MD). Moreover, the annealed films expanded and shrank by approximately 0.5% along the MD and transverse direction (TD), respectively. The unusual expansion behavior during annealing suggests that a small amount of oriented molecular chains formed in the extruded film, and the oriented chains acted as a nucleating agent. Consequently, the molecular orientation along the MD was enhanced owing to the morphological transformation. The oriented chains also acted as nucleating agent during tensile deformation, resulting in a significant improvement of strength in the MD stretching.

Temperature-triggered in situ forming lipid mesophase gel for local treatment of ulcerative colitis

Ulcerative colitis is a chronic inflammatory bowel disease that strongly affects patient quality of life. Side effects of current therapies necessitate new treatment strategies that maximise the drug concentration at the site of inflammation, while minimizing systemic exposure. Capitalizing on the biocompatible and biodegradable structure of lipid mesophases, we present a temperature-triggered in situ forming lipid gel for topical treatment of colitis. We show that the gel is versatile and can host and release drugs of different polarities, including tofacitinib and tacrolimus, in a sustained manner. Further, we demonstrate its adherence to the colonic wall for at least 6 h, thus preventing leakage and improving drug bioavailability. Importantly, we find that loading known colitis treatment drugs into the temperature-triggered gel improves animal health in two mouse models of acute colitis. Overall, our temperature-triggered gel may prove beneficial in ameliorating colitis and decreasing adverse effects associated with systemic application of immunosuppressive treatments.

Coarse-grained modeling of polymers with end-on and side-on liquid crystal moieties: Effect of architecture.

Mesogens, which are typically stiff rodlike or disklike molecules, are able to self-organize into liquid crystal (LC) phases in a certain temperature range. Such mesogens, or LC groups, can be attached to polymer chains in various configurations including within the backbone (main-chain LC polymers) or at the ends of side-chains attached to the backbone in an end-on or side-on configuration (side-chain LC polymers or SCLCPs), which can display synergistic properties arising from both their LC and polymeric character. At lower temperatures, chain conformations may be significantly altered due to the mesoscale LC ordering; thus, when heated from the LC ordered state through the LC to isotropic phase transition, the chains return from a more stretched to a more random coil conformation. This can cause macroscopic shape changes, which depend significantly on the type of LC attachment and other architectural properties of the polymer. Here, to study the structure-property relationships for SCLCPs with a range of different architectures, we develop a coarse-grained model that includes torsional potentials along with LC interactions of a Gay-Berne form. We create systems of different side-chain lengths, chain stiffnesses, and LC attachment types and track their structural properties as a function of temperature. Our modeled systems indeed form a variety of well-organized mesophase structures at low temperatures, and we predict higher LC-to-isotropic transition temperatures for the end-on side-chain systems than for analogous side-on side-chain systems. Understanding these phase transitions and their dependence on polymer architecture can be useful in designing materials with reversible and controllable deformations.

Thermotropic liquid crystalline medicine: establishment of liquid crystalline properties and the X-ray phase structure analysis of immunosuppressant 2-amino-2-[2-(4-alkylphenyl)ethyl]propane-1,3-diol hydrochloride

ABSTRACT From 1995 to 2000, it was found by a pharmaceutical industry that the long-chain-substituted compounds, 2-amino-2-[2-(4-n-alkylphenyl)ethyl]propan-1,3-diol hydrochloride derivatives (abbreviated as Cn-C2-APD (n = 7 ~ 14)), become an excellent immunosuppressant. However, at that time, they only reported that the melting points of these compounds show at ca.107°C irrespective of the chain length (n), and they overlooked that a liquid crystalline phase exists over the melting points. Recently, we have noticed that these immunosuppressive medicines have a molecular structure very similar to a thermotropic liquid crystalline material reported by Borisch et al. in 1998. Therefore, in this work, we have synthesised the same series of the Cn-C2-APD (n = 8 ~ 14) derivatives and investigated the liquid crystallinity and the mesophase structure by using a polarising microscope, DSC, and a temperature-variable X-ray diffractometer. As a result, we have established for the first time that each of the Cn-C2-APD (n = 8 ~ 14) derivative has an SA phase having a bilayer structure in a temperature range from the melting points at ca. 107°C and the decomposition temperature at ca. 230°C, irrespective of the chain length (n).

Molecular Rearrangements in Protomembrane Models Probed by Laurdan Fluorescence.

Lipid membranes are a key component of living systems and have been essential to the origin of life. One hypothesis for the origin of life assumes the existence of protomembranes with ancient lipids formed by Fischer-Tropsch synthesis. We determined the mesophase structure and fluidity of a prototypical decanoic (capric) acid-based system, a fatty acid with a chain length of 10 carbons, and a lipid system consisting of a 1:1 mixture of capric acid with a fatty alcohol of equal chain length (C10 mix). To shed light on the mesophase behavior and fluidity of these prebiotic model membranes, we employed Laurdan fluorescence spectroscopy, which reports on the lipid packing and fluidity of membranes, supplemented by small-angle neutron diffraction data. The data are compared with data of the corresponding phospholipid bilayer systems of the same chain length, 1,2-didecanoyl-sn-glycero-3-phosphocholine (DLPC). We demonstrate that the prebiotic model membranes capric acid and the C10 mix show formation of stable vesicular structures needed for cellular compartmentalization at low temperatures only, typically below 20 °C. They reveal the fluid-like lipid dynamic properties needed for optimal physiological function. High temperatures lead to the destabilization of the lipid vesicles and the formation of micellar structures.

Crystal and mesophase structure of a bicyclohexyl cyano mesogen.

The phase behaviour of 4-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]benzonitrile, C22H31N, 1, has been examined. This compound has two different solid phases, denoted I and II, and exhibits thermotropic liquid-crystalline behaviour, with a remarkable interval of stability of the mesophase between the lower melting solid phase (75 °C) and the isotropization temperature (247 °C). The crystal and molecular structures of solid phase I have been determined at 173 K. The cyclohexyl rings both adopt the chair conformation and are equatorially substituted. The packing of 1 in the crystalline state is driven by the antiparallel arrangement of cyano dipoles with the formation of close contacts involving the strong cyano acceptor and weak aromatic C-H or aliphatic C-H donors. The crystal packing is discussed and compared with X-ray diffraction data in the liquid-crystalline state. The combination of thermal analysis, optical polarizing microscopy and X-ray diffraction analysis suggests that the mesophase is a partially ordered smectic phase. The lamellar structure of the mesophase is retained in crystalline solid phase II obtained by cooling the liquid-crystalline phase.

Switchable magnetic, dielectric, conductivity, and phase transition properties of charge-transfer crystals

The properties can be switched between different states and can be used in sensors, displays, and memory devices. In this study, two multi-functional switchable materials [C5-Pmim][Ni(mnt)2] (1) and [C6-Hmim][Ni(mnt)2] (2) (where mnt2-= maleonitriledithiolate, C5-Pmim = 1-pentyl-3-methylimidazolium, and C6-Hmim = 1-hexyl-3-methylimidazolium) have been designed and synthesized, which has segregated cation and anion stacks in the crystal structure. 1 shows two-step switchable dielectric transition with a thermal hysteresis loop accompanying structure phase transition. Dielectric transition of 1 can be attributed to the reorientation of the polar cations and crystal to mesophase transition. Switchable conductivity properties of 1 and 2 were realized by the crystal to mesophase structure transition. The conductivity of the mesophase for 1 and 2 is higher than the corresponding crystal phase. Furthermore, magnetic phase transition with the non-common hysteresis loop for 2 is observed being triggered by the structure and dielectric transition. To the best of our knowledge, this study might be the rare multi-functional switchable examples with dielectric, conductivity, and magnetic transition.

Preparation of Complex Ratio‐Dependent Nanomaterials from Polymerizable Hydrogen‐Bonded Liquid Crystal

A scalable approach to generating different nanomaterials from the same hydrogen-bondeded complex by photo-crosslinking is described. The hydrogen-bonded complex exhibits a smectic or columnar mesophase, depending on the molar ratio between the donor and acceptor. The mesophase structure is effectively retained after photo-crosslinking. Polymer nanosheets with negatively charged carboxylate groups can be prepared from the complex with the smectic mesophase after subsequent extraction and chemical treatment, and they show effective adsorption of Pd2+. Meanwhile, a nanoporous polymer is successfully achieved from the complex having the columnar mesophase by using the same technology of photo-crosslinking and solvent treatment. This work provides a new strategy to fabricate different nanomaterials from the same hydrogen-bonded complex system.

Lipidic poly(2-oxazoline)s as PEG replacement steric stabilisers for cubosomes

HypothesisCubosomes are promising delivery vehicles for a wide range of drugs and biomolecules. Polymers such as the polyethylene glycol (PEG)-based Pluronic F-127 have been widely used for dispersing and stabilising lipid cubosomes. However, due to the PEG-immunogenicity, and pre-existing anti-PEG antibodies in some individuals, the efficacy of PEG-stabilised nanomedicines has been reduced. In this study, we hypothesise that lipidic poly(2-oxazoline)s have the potential to stabilise cubosomes, which can be used to encapsulate a hydrophobic drug similar to cubosomes stabilised with F-127. ExperimentsTwo lipidic polymers consisting of an oleyl (OA) chain connected to a poly(2-methyl-2-oxazoline) backbone were synthesised using cationic ring-opening polymerisation (PMeOx40-OA and PMeOx80-OA). The PMeOxn-OA stabilised monoolein cubosomes were compared to F-127 cubosomes in particle size, stability, mesophase structure, and biocompatibility. FindingsThe obtained PMeOxn-OA were well-defined (low dispersity) and had a high degree of OA functionalisation (≥95%). These polymers were as good as F-127 in producing well dispersed monoolein cubosomes and maintained the internal cubic structure. The cubosomes stabilised with PMeOxn-OA showed lower cytotoxic effect compared to F-127 stabilised cubosomes against OVCAR-3 cells. Furthermore, the PMeOxn-OA cubosomes significantly improved the solubility of SN-38, a poorly water-soluble cancer drug.

Main-chain side-chain combined liquid crystalline polymers bearing azobenzene and biphenyl-based mesogens – segregation of the mesogens within two distinct layers

ABSTRACT Two different mesogenic units, namely biphenyl and azobenzene, were installed centrally within the polymer backbone and pendant alkylene segments; the purpose was to examine if chain folding of the backbone occurs so as to segregate the azobenzene and biphenyl units in adjacent layers of a smectic-type ordering. Two sets of isomeric main-chain side-chain liquid crystalline polymers (MCSC-LCPs), namely SC-AzoCx-MC-BPCx and SC-BPCx-MC-AzoCx (x=6 or 10), were synthesised; the former series has biphenyl in the backbone and azobenzene in the side-chain, while their locations are switched in the latter. It was observed that all four polymers were semicrystalline at room temperature and exhibited a smectic mesophase upon melting. DSC and X-ray scattering studies revealed that switching the locations of the azobenzene and biphenyls had little effect on; the phase transition temperatures and smectic layer spacings. A second series, namely SC-AzoCx-MC-BPCy and SC-BPCx-MC-AzoCy, where the length of alkylene spacers in the side-chain (Cx) and backbone (Cy) is different, was also studied; this was done to examine the influence of unequal alkylene segment lengths on the mesophase structure and interlayer spacing, and importantly, whether the zigzag folding-induced formation of a layered structure is retained, despite their unsymmetrical nature.

2,7-substituted fluorenone-based liquid crystal trimers: twist-bend nematic phase induced by outer thioether linkage

ABSTRACT 2,7-Substituted fluorenone has a planar and slightly bent aromatic structure and is used as a building block for organic liquid crystals (LCs). Herein, we report for the first time the synthesis, phase-transition behaviour, and mesophase structure of fluorenone-incorporated LC trimers that exhibit an emerging helical twist-bend nematic (NTB) phase. The LC trimers possess a central 2,7-ether-substituted fluorenone and bilateral cyanobiphenyl groups linked via odd alkylene C n H2n spacers (n = 7 or 9) with either ether or thioether outer linkages; these are abbreviated CBOnOFlnOnOCB and CBSnOFlnOnSCB, respectively. The CBOnOFlnOnOCB trimers having only ether linkages display only the conventional nematic (N) phase, whereas the outer thioether-linked CBSnOFlnOnSCB trimers form an NTB phase below the temperature range of the N phase. Furthermore, the phase-transition behaviour of these fluorenone-based LC trimers is compared with that of the corresponding all-biphenyl-based motif trimer analogues, CBOnOBOnOCB and CBSnOBOnSCB.

Thioether-Linked Liquid Crystal Trimers: Odd-Even Effects of Spacers and the Influence of Thioether Bonds on Phase Behavior.

We report the synthesis, phase-transition behavior, and mesophase structures of the first homologous series of thioether-linked liquid crystal (LC) trimers, 4,4′-bis[ω-(4-cyanobiphenyl-4′-ylthio)alkoxy]biphenyls (CBSnOBOnSCB with a wide range of spacer carbon numbers, n = 3–11). All CBSnOBOnSCB homologs exhibited LC phases. Interestingly, even-n and odd-n homologs showed monotropic layered smectic A (SmA) and pseudo-layered twist-bend nematic (NTB) phases, respectively, below a nematic (N) phase. This alternate formation, which depends on spacer chain parity, is attributed to different average molecular shapes, which are associated with the relative orientations of the biphenyl moieties: linear and bent shapes for even-n and odd-n homologs, respectively. In addition, X-ray diffraction analysis indicated a strong cybotactic N phase tendency, with a triply intercalated structure. The phase-transition behavior and LC phase structures of thioether-linked CBSnOBOnSCB were compared with those of the all-ether-linked classic LC trimers CBOnOBOnOCB. Overall, thioether linkages endowed CBSnOBOnSCB with a monotropic LC tendency and lowered phase-transition temperatures, compared to those of CBOnOBOnOCB, for the same n. This is attributed to enhanced flexibility and bending (less molecular anisotropy) of the molecules, caused by the greater bond flexibility and smaller inner bond angles of the C–S–C bonds, compared to those of the C–O–C bonds.

Engineering mesophase stability and structure via incorporation of cyclic terminal groups

The installation of an aliphatic ring at the end of the alkyl chain for a family of 4-alkoxy-4′-cyanobiphenyl liquid crystals is shown to enhance clearing points and promotes the formation of smectic phases, relative to the linear parent materials.