Search Results (106)

The present study focuses on the effect of doping KH560-modified cellulose nanocrystals (CNCs) on the electro-optical characteristics of polymer-dispersed liquid crystals (PDLCs). PDLC films were fabricated through the polymerization-initiated phase separation (PIPS) process and doped with CNC nanoparticles at various concentrations. At low concentrations, the CNCs at the interface, by virtue of their unique chiral characteristics, induce an orderly arrangement of liquid crystal molecules. Meanwhile, the interaction between the film’s fiber structure and the liquid crystal droplets brings about an augmentation in the arrangement efficiency. The excellent dispersion of CNCs diminishes the random alignment of liquid crystal molecules and mitigates light scattering. Additionally, it aids in the deflection of the liquid crystal director, facilitating the lubrication of the liquid crystals’ movement. It is remarkable that within the range of relatively lower CNCs doping concentrations, specifically from 0.005 wt% to 0.05 wt%, the PDLC films exhibit lower threshold and saturation voltages, faster response, enhanced viewing angle performance and higher contrast. Full article

This study was conducted at SPINLab. The full-scale experiments were performed using two experimental spaces of identical specifications to investigate the effects of electrochromic film (OG + EC_ON or OG + EC_OFF) on indoor environment and air conditioning electricity consumption in buildings with different orientations (East and West). The electricity-saving effects are more pronounced on the building’s west-facing side than on its east-facing side. For the east-facing side, the average electricity savings for OG + EC_ON and OG + EC_OFF were 4.5%, and 5.1%, respectively. For the west-facing side, the average electricity savings increased to 9.2% and 9.4% for OG + EC_ON and OG + EC_OFF. The research results on thermal comfort indicate (PMV) that applying electrochromic film (OG + EC_ON or OG + EC_OFF) significantly improved indoor thermal comfort compared to using clear glass (OG) alone. The visual comfort analysis results indicate that the opaque (OG + EC_OFF) and transparent (OG + EC_ON) states of electrochromic film could reduce daylight glare probability (DGP) values. However, due to the light-scattering properties of the liquid crystal droplets, the OG + EC_OFF and OG + EC_ON states of the electrochromic film increased DGP values in 26.5% and 41.5% of the cases, respectively, when sunlight directly entered the interior. Full article

This study prepared palm stearin/linseed oil-based margarines (PST/LO-BMs) and palm stearin/linseed oil oleogel-based margarines (PST/LO-OBM) by incorporating varying proportions (20–60% oil phase) of linseed oil (LO) and LO-based oleogel, respectively. By comparing PST/LO-OBMs and PST/LO-BMs, it was found that the introduction of phytosterol–γ-oryzanol (PO) complexes and glycerol monostearate (GMS) to PST/LO-OBM induced three distinct crystalline morphologies: needle-like crystals, spherical crystals, and cluster-type crystals. These crystal assemblies synergistically constructed a robust three-dimensional network, effectively entrapping both aqueous droplets and liquid oil fractions while substantially reinforcing the structural integrity of PST/LO-OBM. Notably, the incorporated gelators modified the crystallization behavior, where GMS likely served as a nucleating site promoting triglyceride crystallization. This structural modulation yielded favorable β’-form crystal polymorphism, which is critically associated with enhanced textural properties. Comparative analysis with commercial margarine revealed that the PST45/LO40-OBM formulation exhibited comparable rheological performance, crystalline type, and thermal properties, while demonstrating superior nutritional characteristics, containing elevated levels of α-linolenic acid (23.54%), phytosterol (1410 mg/100 g), and γ-oryzanol (2110 mg/100 g). These findings provide fundamental insights for margarine alternatives with nutritional attributes. Full article

By monitoring the solidification of droplets of plant latices with a fast quartz crystal microbalance with dissipation monitoring (QCM-D), droplets from Campanula glomerata were found to solidify much faster than droplets from Euphorbia characias and also faster than droplets from all technical latices tested. A similar conclusion was drawn from optical videos, where the plants were injured and the milky fluid was stretched (sometimes forming fibers) after the cut. Rapid solidification cannot be explained with physical drying because physical drying is transport-limited and therefore is inherently slow. It can, however, be explained with coagulation being triggered by a sudden decrease in hydrostatic pressure. A mechanism based on a pressure drop is corroborated by optical videos of both plants being injured under water. While the liquid exuded by E. characias keeps streaming away, the liquid exuded by C. glomerata quickly forms a plug even under water. Presumably, the pressure drop causes an influx of serum into the laticifers. The serum, in turn, triggers a transition from a liquid–liquid phase separated state (an LLPS state) of a resin and hardener to a single-phase state. QCM measurements, optical videos, and cryo-SEM images suggest that LLPS plays a role in the solidification of C. glomerata. Full article

Amorphous solid dispersion (ASD) is one of the most important enabling formulation technologies for the development of poorly soluble drugs. Because of its thermodynamically unstable nature in both solid and wet states, the evaluation and optimization of the formulation performance involves some difficulties. The dissolution process is sensitively influenced by various factors, including the applied dose, medium composition, and pH. Supersaturated solutions can cause liquid–liquid phase separation (LLPS) and/or crystallization, which complicates the comprehension of the dissolution process. However, LLPS should be evaluated carefully because it is closely related to oral absorption. As LLPS concentration is analogous to amorphous solubility, it can be a key factor in predicting oral absorption from ASDs, if absorption is limited by solubility. Moreover, LLPS droplets are expected to increase transmembrane flux by increasing the drug concentration near the epithelial cell membrane. In this review, recently updated knowledge on the dissolution, membrane permeation, and oral absorption behaviors of ASDs is discussed with an emphasis on LLPS behavior. Full article

Monolayer nanosheets of zirconium phosphate in aqueous suspension exhibit short-range repulsion and long-range attraction, producing, at overall volume fractions larger than about half a percent, phase separation into higher-concentration liquid crystal and lower-concentration isotropic regions. At high concentrations, this phase separation takes the form of an emulsion of condensed, liquid-crystalline droplets, which anneal to form lens-shaped tactoids. These tactoids provide an opportunity to study the liquid crystal ordering of inorganic nanosheets in the limit of large shape anisotropy (diameter/thickness~400) and high packing fraction (volume fraction $\gtrsim$ 70%). The internal liquid crystal structure of the tactoids remains nematic even under conditions that would usually favor ordering into lamellar smectics. Local lamellar ordering is suggested by short-range, smectic-like layer correlations, but a full transition into a smectic phase appears to be inhibited by the nanosheet edges, which act as a perturbative population of dislocation loops in the system of layers. Under conditions of thermal equilibrium, the nanoplates organize positionally to enable bend deformation of the director, a hallmark of the nematic phase and its principal distinction from the smectic, where bend must be expelled. Full article

Liquid crystal (LC) droplets are highly attractive for applications in privacy windows, optical switches, optical vortices, optical microresonators, microlenses, and biosensors due to their ease of fabrication and easy alignment at surfaces. This review presents the latest advancements in LC droplets, which have nematic, chiral nematic, and twist–bend nematic and ferroelectric nematic phases, or blue phases. Finally, it discusses the challenges and opportunities for applications based on LC droplets. The main challenges encompass the precise control of internal structures and defects to meet diverse application requirements, enhancing stability and durability across various environments, reducing large-scale production costs to improve commercial feasibility, increasing response speeds to external stimuli to adapt to rapidly changing scenarios, and developing tunable LC droplets to achieve broader functionalities. Full article

Drying–wetting cycles play a crucial role in the investigation of the origin of life as processes that both concentrate and induce the supramolecular assembly and polymerization of biomolecular building blocks, such as nucleotides and amino acids. Here, we test different microfluidic devices to study the dehydration–hydration cycles of the aqueous solutions of small molecules, and to observe, by optical microscopy, the insurgence of phase transitions driven by self-assembly, exploiting water pervaporation through polydimethylsiloxane (PDMS). As a testbed, we investigate solutions of the chromonic dye Sunset Yellow (SSY), which self-assembles into face-to-face columnar aggregates and produces nematic and columnar liquid crystal (LC) phases as a function of concentration. We show that the LC temperature–concentration phase diagram of SSY can be obtained with a fair agreement with previous reports, that droplet hydration–dehydration can be reversibly controlled and automated, and that the simultaneous incubation of samples with different final water contents, corresponding to different phases, can be implemented. These methods can be further extended to study the assembly of diverse prebiotically relevant small molecules and to characterize their phase transitions. Full article

The solidification of Inconel 718 alloy (IN718) from undercooled liquid is studied. The solidification kinetics is evaluated in melted and undercooled droplets processed using the electromagnetic levitation (EML) technique by the temperature–time profiles and solid/liquid (S/L) interface movement during recalescence. The kinetics is monitored in real time by special pyrometrical measurements and high-speed digital camera. It is shown that the growth velocity of $\gamma$-phase (the primary phase in IN718), the final crystalline microstructure (dendritic and grained), and the mechanical properties (microhardness) are strongly dependent on the initial undercooling $\Delta T$ at which the samples started to solidify with the originating $\gamma$-phase. Particularly, with the increase in undercooling, the secondary dendrite arm spacing decreases from 28 μm to 5 μm. At small and intermediate ranges of undercooling, the solidified droplets have a dendritic crystalline microstructure. At higher undercooling values reached in the experiment, $\Delta T>160$ K (namely, for samples solidified with $\Delta T=170$ K and $\Delta T=263$ K), fine crystalline grains are observed instead of the dendritic structure of solidified drops. Such change in the crystalline morphology is qualitatively consistent with the behavior of crystal growth kinetics which exhibits the change from the power law to linear law at $\Delta T\approx 160$ K in the velocity–undercooling relationship (measured by the advancement of the recalescence front in solidifying droplets). Study of the local mechanical properties shows that the microhardness increases with the increase in the ${\gamma }^{″}$-phase within interdendritic spacing. The obtained data are the basis for testing the theoretical and computational of multicomponent alloy samples. Full article

The development of optical and photonic applications using soft-matter droplets holds great scientific and application importance. The machining of droplet structures is expected to drive breakthroughs in advancing frontier applications. This review highlights recent advancements in micro–nanofabrication techniques for soft-matter droplets, encompassing microfluidics, laser injection, and microfluidic 3D printing. The principles, advantages, and weaknesses of these technologies are thoroughly discussed. The review introduces the utilization of a phase separation strategy in microfluidics to assemble complex emulsion droplets and control droplet geometries by adjusting interfacial tension. Additionally, laser injection can take full advantage of the self-assembly properties of soft matter to control the spontaneous organization of internal substructures within droplets, thus providing the possibility of high-precision customized assembly of droplets. Microfluidic 3D printing demonstrates a 3D printing-based method for machining droplet structures. Its programmable nature holds promise for developing device-level applications utilizing droplet arrays. Finally, the review presents novel applications of soft-matter droplets in optics and photonics. The integration of processing concepts from microfluidics, laser micro–nano-machining, and 3D printing into droplet processing, combined with the self-assembly properties of soft materials, may offer novel opportunities for processing and application development. Full article

The research program “Engineered Artificial Minerals (EnAM)” addresses the challenge of recycling valuable elements from battery waste streams. These elements, such as lithium (Li), often migrate in the slag phase, in some cases as crystals. EnAM crystals represent concentrated reservoirs of these elements, which can only be effectively recycled if they are extracted from the slag matrix and then separated. Selective wet agglomeration is a separation process based on a three-phase system and is often used in coal and ore processing. The produced agglomerates in this process can be easily separated from the remaining suspension. The precise quantification of the wetting properties and adhesion strength between suspended particles and binding liquid droplets is a scientific challenge. An accurate technique suitable for adhesion force measurements in three-phase systems with micrometer-scale particles is Fluidic Force Microscopy (FluidFM^®). An experimental setup with optical control is being developed to measure adhesion forces between droplets and flat/rough surfaces. This will enable precise measurements of adhesion forces between solid EnAM crystals and binding liquid droplets. Based on these measurements, optimal agglomeration conditions can be selected in the future to improve selective wet agglomeration with respect to recycling processes. Full article

In this work, we report on measurements of the contact angle of sessile droplets of aqueous solutions of a chromonic liquid crystal at different temperatures and concentrations and on different hydrophobic surfaces, and we show that the wettability of this complex fluid can be easily controlled by an external electric field. Specifically, electrically induced variations of the contact angle up to 70° were obtained using external DC voltages. Complementary tensiometric measurements of the aqueous solutions confirmed that the observed variations in the contact angle were mainly related to variations in the surface tension, while they did not show an evident connection with the internal molecular order of the liquid crystal droplets. Our study is relevant in view of the use of chromonic liquid crystals in microfluidic devices, where the control of wettability is an important tool for handling fluid flow. Full article

Interactions between liquid crystal molecules and target analytes open up various biosensing applications for quick screening and point-of-care applications. In this review, we categorized biosensors by type, depending on the liquid crystal mesophase, and considered several applications for the detection of biomolecules, point-of-care diagnostics and environmental monitoring. We also discuss interactions between polarized light and target pathogens dispersed in biological fluids, which result in the change of the polarization state. An array of the Stokes parameters can be compared with the pattern, and a proper pathogen can be manifested. We suggest that a combination of a micropolarizer array and a complementary metal oxide semiconductor sensor is an optimal setup for the detection of pathogens. Herein, we discuss the working principles of liquid crystal biosensors and their fabrication principles. In addition, relevant theoretical and practical issues related to liquid crystal biosensors are outlined. In general, this review gives an in-depth survey of the research on liquid crystal-based sensors, making it easier for researchers to locate their niche and make contributions to this subject from multiple viewpoints. Full article

Coalescence of nanowires and other three-dimensional structures into continuous film is desirable for growing low-dislocation-density III-nitride and III-V materials on lattice-mismatched substrates; this is also interesting from a fundamental viewpoint. Here, we develop a growth model for vertical nanowires which, under rather general assumptions on the solid-like coalescence process within the Kolmogorov crystallization theory, results in a morphological diagram for the asymptotic coverage of a substrate surface. The coverage is presented as a function of two variables: the material collection efficiency on the top nanowire facet $a$ and the normalized surface diffusion flux of adatoms from the NW sidewalls $b$. The full coalescence of nanowires is possible only when $a=1$, regardless of $b$. At $a>1$, which often holds for vapor–liquid–solid growth with a catalyst droplet, nanowires can only partly merge but never coalesce into continuous film. In vapor phase epitaxy techniques, the NWs can partly merge but never fully coalesce, while in the directional molecular beam epitaxy the NWs can fully coalesce for small enough contact angles of their droplets corresponding to $a=1$. The growth kinetics of nanowires and evolution of the coverage in the pre-coalescence stage is also considered. These results can be used for predicting and controlling the degree of surface coverage by nanowires and three-dimensional islands by tuning the surface density, droplet size, adatoms diffusivity, and geometry of the initial structures in the vapor–liquid–solid, selective area, or self-induced growth by different epitaxy techniques. Full article

Elongated ellipsoidal liquid crystal microdroplet reorientation dynamics are discussed in this paper for biosensor applications. To investigate the effect of elongated droplets on nematic liquid crystal droplet biosensors, we simulated a model of a liquid crystal droplet using ellipse geometry. Director reorientation is examined in relation to the elongated droplet shape. In addition, we examined aspect ratio as a factor affecting biosensor response time in relation to surface viscosity and anchoring energy. Finally, the findings suggest that the aspect ratio should be taken into account when designing biosensors. These results can be used to develop more effective biosensors for a variety of applications. This model then predicts the director reorientation angle, which is dependent on the anchoring energy and surface viscosity. This model further suggests that both surface viscosity and homeotropic anchoring energy play an important role when it comes to the director reorientation angle. We developed and applied a nonlinear unsteady-state mathematical model utilizing torque balance and Frank free energy according to the Leslie–Ericksen continuum theory for simulating elongated nematic liquid crystal biosensor droplets with aqueous interfaces. Using the Euler–Lagrange equation, a transient liquid crystal–aqueous interface realignment is modeled by changing the easy axis when surfactant molecules are added to the interface. The realignment at the surface of the droplet is assumed to be driven by the effect of the surfactant, which causes an anchoring transition. According to the results, the response time of the biosensor depends on the aspect ratio. Therefore, the elongation has the potential to control biosensing response time. The result of our study provides a better understanding of director reorientation in elongated liquid crystal droplets in biosensing applications through the numerical results which are presented in this paper. Full article