New temperature dependent X-ray diffraction (XRD) data on the bent-core mesogens based nonlinear 2,5-bis(p-hydroxyphenyl)-1,3,4-oxadiazole (ODBP) unit enable a consistent interpretation of supramolecular structure in this class liquid crystals. Strong evidence for cybotaxis high phase explains small-angle four-spot pattern and calls into question prior XRD interpretations. We find that can be satisfactorily explained by skewed cybotaxis, stratified arrangement tilted, (BCMs). also observe...

Lyotropic cubic liquid-crystalline systems have received increasing attention due to their unique microstructural and physicochemical properties as efficient nanocarriers for drug delivery. We report the preparation characterization of bulk phases cubosome dispersions phytantriol loaded with anticancer 5-fluorouracil, in neutral anionic forms. In both cases, a Pn3m phase was observed. The behavior can be influenced by addition ionic agents, and, this purpose, positively charged lipid, such...

Cybotaxis, the molecular clustering observed in bent-core nematics, governs unique properties of this new class anisotropic fluids.

The self-assembly of asymmetric polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) block copolymer based nanoporous thin films over a broad range molar mass (Mn) between 39 kg·mol–1 and 205 is obtained by means simple thermal treatment. In the case standard treatments, process copolymers hindered at small Mn thermodynamic limitations large kinetic barrier high Mn. We demonstrate that fine tuning annealing parameters, performed Rapid Thermal Processing (RTP) machine, permits us to overcome...

A bent-core mesogen that forms a cybotactic nematic phase exhibits giant magnetic field-induced shift of its nematic-isotropic and smectic-$C$--nematic transition temperatures: $\ensuremath{\Delta}T(H)=4\text{ }\text{ }\mathrm{K}$ for $H=10\text{ }\mathrm{kOe}$. In contrast with molecular nematics, in nematics the field couples anisotropic susceptibility clusters containing several hundred partially ordered molecules. X-ray diffraction data corroborate quantitative estimate inferred cluster...

As part of our efforts to access the biaxial nematic phase at low temperatures, we prepared a series 1,3,4-oxadiazole-based bent-core mesogens that possess either one or three lateral methyl groups. The behavior these derivatives was characterized using polarizing microscopy and differential scanning calorimetry. Target compounds containing group showed large ranges but relatively high clearing points. with substituents lower onset temperatures two supercooled in room temperature. X-ray...

Abstract Combining polymers with small amounts of stiff carbon-based nanofillers such as graphene or oxide is expected to yield low-density nanocomposites exceptional mechanical properties. However, have remained elusive because incompatibilities between fillers and that are further compounded by processing difficulties. Here we report a water-based process obtain highly reinforced nanocomposite films simple mixing two liquid crystalline solutions: colloidal nematic phase comprised platelets...

The possibility of biaxial orientational order in nematic liquid crystals is a subject intense current interest. We explore the tendencies toward local and global ordering recently synthesized trimethylated oxadiazole-based bent-core mesogens with pronounced asymmetric (bow-type) shape molecules. combination x-ray diffraction optical studies suggests that expressed differently at short- long-range scales. Locally, scale few molecules, x-ray-diffraction data demonstrate packing. However,...

AbstractHerein we review the attributes of cluster biaxial nematic exhibited by bent-core mesogens derived from oxadiazole biphenol mesogenic core. We present an array static 2H NMR spectra as well 2D powder generated rotating phase directly labelled mesogens. Analysis these motionally averaged observations requires to have monoclinic symmetry. X-ray diffraction data, in particular effects electric and magnetic field effects, are also consonant with picture this phase.Keywords: liquid...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTEvidence of Biaxial Order in the Cybotactic Nematic Phase Bent-Core MesogensFrancesco Vita†, Tatum Tauscher‡, Frank Speetjens‡, Edward T. Samulski§, Eric Scharrer‡, and Oriano Francescangeli*†View Author Information† Dipartimento SIMAU CNISM, Università Politecnica delle Marche, via Brecce Bianche, 60131 Ancona, Italy‡ Department Chemistry, University Puget Sound, 1500 N. Warner, Tacoma, Washington 98416,United States§ North Carolina,...

The phase behaviour in thin films of an asymmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA) block copolymer with a molecular weight 39 kg mol−1 was assessed at wide range temperatures and times. Cylindrical PMMA structures featuring diameter close to 10 nm perpendicularly oriented respect the substrate were obtained 180 ° C relatively short annealing times (t ≤ 30 min) by means simple thermal treatment performed standard rapid processing machine.

Abstract A commercial variable angle spectroscopic ellipsometer from J. A. Woollam Company is modified in order to make possible measurements guiding structures. The half leaky guided mode technique realised for liquid crystal optical dispersion measurements. Features and problems related experimental data interpretation error sources the refractive index are carefully analyzed, achieving a final accuracy of ±0.0002. We present measured curves wavelength range 0.5 1.7 μm two widely studied...

High-resolution holographic gratings are obtained using a combination of multifunctional acrylate (DPHP/HA), low-molecular-weight glass-forming liquid epoxy-aromatic resin (TPMTGE), and UV-photoinitiator (Irgacure 819). Their optical properties (sensitivity, transparency, shrinkage) promising for high-density data storage applications.

We report the synthesis and structural characterization of a main-chain liquid crystal polymer constituted by 1,2,4-oxadiazole-based bent-core repeat unit. For first time, made bent mesogenic units is demonstrated to exhibit cybotactic order in nematic phase. Coupled with chain-bond constraints, cybotaxis results maximized molecular correlations that make this material great potential search for elusive biaxial ferroelectric phases. Indeed, repolarization current measurements phase hint at...

We have investigated the effects of a low frequency electric field on thermotropic behavior nematogenic bent-core liquid crystal by means X-ray diffraction. determined for first time 2D phase diagram mesogen over an extended temperature-field (T, E) space. The results show that strongly affects both mesophase sequence and transition temperatures sample. An extraordinary field-induced shift nematic–isotropic is found, which has neither any experimental counterpart in conventional calamitic...

We have previously demonstrated that the incorporation of lateral methyl groups on oxadiazole-based liquid crystals leads to relatively low-temperature cybotactic nematic phases which, in some cases, supercool room temperature. report here synthesis and phase behaviour related compounds possess halogen as well. Derivatives with three substituents (one two groups) a specific pattern As was case reported trimethylated derivatives, is glassy nature. Two new trisubstituted derivatives (with...

Block copolymer (BCP) self-assembly is expected to complement conventional optical lithography for the fabrication of next-generation microelectronic devices. In this regard, silicon-containing BCPs with a high Flory–Huggins interaction parameter (χ) are extremely appealing because they form high-resolution nanostructures characteristic dimensions below 10 nm. However, due their slow kinetics and low thermal stability, these high-χ usually processed by solvent vapor annealing or in...

Since its theoretical prediction in 1970, the search for biaxial nematic phase thermotropic systems has challenged generations of liquid crystal scientists. Over last 10 years, bent-core mesogens have drawn much interest as promising candidates biaxiality. However, despite a number disputed claims, conclusive evidence proper (spontaneous and macroscopic) order these materials is still missing. By contrast, it now widely recognised that biaxiality exists on local scale, form nano-sized...

Soft materials exhibit very attractive mechanical, optical, and electro-optical properties easy processing techniques. Combined with holographic techniques, they can be patterned quite easily creating many unique structures. We present here few examples, of electrically-switchable passive opto-electronic components based on composite obtained from initial mixtures photocurable monomers liquid crystalline materials. Holographic exposure results in volume gratings consisting alternate areas...

In this paper, we present our results for the anisotropic refractive index measurements of commonly used liquid crystal (LC) materials (E7 and 5CB) in whole visible–near infrared range. order to achieve a high accuracy obtained values, have employed combination two techniques, namely, Mueller matrix spectroscopic ellipsometry transmission half-leaky-guided-mode (HLGM). Measurements with HLGM technique are usually performed at single wavelength. obtain measurement based on wide wavelength...

We report the transition temperatures for several series of structural variations on bent-core mesogens (BCMs) derived from asymmetric oxazole biphenol mesogenic core. Trimethyl-substituted exhibit nematic phases that can be supercooled to room temperature. Preliminary X-ray diffraction (XRD) results confirm a cybotactic supramolecular organisation in these nematics; moreover, splitting diffuse wide-angle XRD feature observed trimethylated points an enhanced biaxial orientational correlation...