Gel Crystallization Research Articles

Crystal growth and characterization of Cd doped copper tartrate crystals in silica gel

Crystal growth and characterization of Cd doped copper tartrate crystals in silica gel

Influence of starch on freeze-thaw stability of Hypophthalmichthys molitrix surimi gel observed via ice crystal distribution and gel properties

Starch has been recognized as a vital ingredient in surimi products due to its ability to absorb water, which reduces the deterioration of gels and water loss during freezing and thawing. However, it is essential to ascertain the role of starch in the formation of ice crystals and the texture of surimi gels. The impact of freeze-thaw cycles on the morphology and distribution of ice crystals, as well as the textural characteristics of gelatinized and ungelatinized starch-surimi gels was investigated. The results of light microscopy revealed that the presence of starch, irrespective of whether it was gelatinized, resulted in a reduction in the size of ice crystals within the surimi gel network during the freeze-thaw process. In addition, starch in surimi gels was subjected to freeze-thaw cycles, resulting in the emergence of two distinct states of bound water (0.1–1 ms and 1–10 ms). The higher relative content of immobile water indicated that the gelatinized starch had improved water holding properties. Furthermore, the incorporation of gelatinized starch into surimi enhanced its freeze-thaw stability and retarded the loss of gel strength, hardness, and whiteness. The addition of starch had a synergistic impact, enhancing the gel properties by affecting the formation of ice crystals and water absorption.

Facile assembly of flexible, stretchable and attachable symmetric microsupercapacitors with wide working voltage windows and favorable durability

With the increasing development of intelligent robots and wearable electronics, the demand for high-performance flexible energy storage devices is drastically increasing. In this study, flexible symmetric microsupercapacitors (MSCs) that could operate in a wide working voltage window were developed by combining laser-direct-writing graphene (LG) electrodes with a phosphoric acid-nonionic surfactant liquid crystal (PA-NI LC) gel electrolyte. To increase the flexibility and enhance the conformal ability of the MSC devices to anisotropic surfaces, after the interdigitated LG formed on the polyimide (PI) film surface, the devices were further transferred onto a flexible, stretchable and transparent polydimethylsiloxane (PDMS) substrate; this substrate displayed favorable flexibility and mechanical characteristics in the bending test. Furthermore, the electrochemical performances of the symmetric MSCs with various electrode widths (300, 400, 500 and 600 μm) were evaluated. The findings revealed that symmetric MSC devices could operate in a large voltage range (0–1.5 V); additionally, the device with a 300 μm electrode width (MSC-300) exhibited the largest areal capacitance of 2.3 mF cm−2 at 0.07 mA cm−2 and an areal (volumetric) energy density of 0.72 μWh cm−2 (0.36 mWh cm−3) at 55.07 μW cm−2 (27.54 mW cm−3), along with favorable mechanical and cycling stability. After charging for ~20 s, two MSC-300 devices connected in series could supply energy to a calculator to operate for ~130 s, showing its practical application potential as an energy storage device. Moreover, the device displayed favorable reversibility, stability and durability. After 12 months of aging in air at room temperature, its electrochemical performance was not altered, and after charging-discharging measurements for 5000 cycles at 0.07 mA cm−2, ~93.6% of the areal capacitance was still retained; these results demonstrated its practical long-term application potential as an energy storage device.

Topical Delivery of Voriconazole Loaded on Lyotropic Liquid Crystal Gel for Management of Fungal Infections

Topical antifungal therapy is recommended for the treatment of fungal infections of the skin. Due to its benefits, including the ability to direct drugs to the infection site and a lower chance of systemic adverse effects. The nano size and structure of LLC with the skin enhance the permeation and deposition of drugs within deep parts of skin. In this a novel formulation of voriconazole LLC gel was planned. Surfactant, co-surfactant, oil, and water pseudo-ternary phase diagrams were created in order to determine the LLC gel and microemulsion zones. The formulations were evaluated using polarizing microscopy, FT-IR spectroscopy. For each formulation, the polydispersity index, zeta potential, and mean droplet size were determined. The release patterns revealed that the prepared LLC gel provide sustained release profile up to 24 hr. Ex-vivo permeation of selected formulations exhibited higher permeability values for voriconazole. The drug skin deposition results from selected formulations showed that, in comparison to other studied formulations, a much larger amount of the drug was deposited in the skin after 24 hours. The confocal pictures appeared that the LLC gel was able to provide fluorescent color to all skin layers. The skin irritation study data of LLC gel formulations could be announced as safe and non- irritant for human skin. The selected formulations underwent a six-month stability testing at room temperature and 4–8 °C. The results showed that the pH, drug content, and viscosity values did not change significantly during this time. Keywords: Lyotropic liquid crystal, Release and diffusion, Skin permeability, Skin deposition, Pathohistology

A Photonic Crystal Gel for Naked-Eye Detection of Uric Acid with High Sensitivity and Specificity

A Photonic Crystal Gel for Naked-Eye Detection of Uric Acid with High Sensitivity and Specificity

Reverse mode LCPG films with self-assembly support of gel networks

ABSTRACT Liquid crystal physical gels (LCPG) with a 3D network structure show considerable promise as novel functional materials with a great impact on scientific and practical applications. LCPGs are not characterised by high hardness and high strength, but this mild nature is capable of forming dynamic supramolecular structures with the self-assembly ability of various non-covalent bonds such as hydrogen bonding, π-π stacking, and van der Waals forces. In addition to anisotropic changes under optical and electrical stimulation, it enables to be one of the candidates for display devices. When the isotropic-anisotropic transition temperature of LCPG solution (TIA) is higher than the sol-gel transition temperature of gel molecules (TSG), the gelation can anchor the orientation of liquid crystal molecules to achieve the alteration of transparency and scattering of the film. In this paper, reverse mode LCPG films with high contrast, low driving voltage, and excellent cycle life were prepared using oriented liquid crystal cassettes and LCPG solutions, it also focused on the effects of chiral compounds (S)-octan-2-yl 4-((4-(hexyloxy)benzoyl)oxy)benzoate (S811) and gel 1,3:2,4-bis-0-(3,4-dimethylbenzylidene)sorbitol (DMDBS) content on electro-optical properties of LCPG films as well as the different functions of TIA and TSG on film orientation.

Effect of Hydrogen Bonding and Chirality in Star-Shaped Molecules with Peripheral Triphenylamines: Liquid Crystal Semiconductors and Gels.

Organic semiconductors with well-defined architectures pose a suitable alternative to amorphous silicon-based inorganic semiconductors. Encouraged by the development of organic semiconductors based on columnar liquid crystals, herein, we report on a family of C3-symmetric star-shaped mesogens based on triphenylamine (TPA), a functional unit with strong electron donor character. Highly stable columnar phases with high hole mobility values were obtained out of this nonplanar functional unit, and this was achieved by using flexible amide spacers to join the TPA units to a tris(triazolyl)triazine (T) star-shaped core, allowing the formation of intermolecular hydrogen bonds. The presence of hydrogen bonds results in a stabilization of the columnar architectures either in bulk or in the presence of solvents by reinforcing π-stacking and van der Waals interactions, as deduced by Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) studies. Furthermore, the introduction of a stereogenic center in the flexible spacer prompts the formation of chiral aggregates in the liquid crystal state and in the organogel formed in 1-octanol, as demonstrated by circular dichroism spectroscopy.

Genetic Diversity of Mangrove and Nypa Palm Species in the Niger Delta, Nigeria

Mangroves and nypa palm are two dominant coastal vegetation in the Niger delta that are sources of numerous ecosystem services. We thus hypothesized that both species are monophyletic, which means they are identical by descent. We began the study by randomly collecting fresh leave samples of nypa palm in a mixed forest comprising nypa palm and mangrove at a coastal community called Eagle Island. We put the leaves samples in zip lock bags containing silica gel crystals and transported them to the laboratory, where the DNA of the leaves was extracted. A quick-DNA plant/seed miniprep kit (Zymo-research Lab, California, USA). A total of six primer pairs were used for the amplification, namely: three microsatellite markers and three universal primers. Fragments of the samples were sequenced using the Ninagen, Brilliant DyeTM Terminator Cycle Sequencing kit V3.1 BRD3-100/1000. All three samples of the nypa palm were amplified, and the BLAST prediction tool was used to produce the new species. Our results show that out of the three samples sequenced (NI, N2, and N3), the N1 sample was identified as Nypa fruticans with 100% identity (Accession Number is KT312925.1), while the others were the new strains identified in the study namely N2 identified as Astrocaryum aculeatum with 98.95% identity (Accession Number is NC 044482.1) and N3 identified as Astrocaryum aculeatum with 99.21% (Accession Number is 044482.1).

Time Dependence of Gel Formation in Lyotropic Nematic Liquid Crystals: From Hours to Weeks.

The combination of lyotropic liquid crystals (LLCs) and low-molecular-weight gelators (LMWGs) for the formation of lyotropic liquid crystal gels (LLC gels) leads to a versatile and complex material combining properties of both parent systems. We gelled the calamitic nematic NC phases of a binary and ternary system using the LMWG 3,5-bis-(5-hexylcarbamoyl-pentoxy)-benzoic acid hexyl ester (BHPB-6). This binary system consists of the surfactant N,N-dimethyl-N-ethyl-1-hexadecylammonium bromide (CDEAB) and water, whereas the ternary system consists of the surfactant N,N,N-trimethyl-N-tetradecylammonium bromide (C14TAB), the cosurfactant n-decanol, and water. Though containing similar surfactants, the gelled NC phases of the binary and ternary systems show differences in their visual and gel properties. The gelled NC phase of the binary system remains clear for several days after preparation, whereas the gelled NC phase of the ternary system turns turbid within 24 h. We investigated the time evolution of the gel strength with oscillation rheology measurements (a) within the first 24 h and (b) up to two weeks after gel formation. The shape of the fibers was investigated over different time scales with freeze fracture electron microscopy (FFEM). We demonstrate that despite their similarities, the two LLC gels also have distinct differences.

Thermal stability and strength degradation of lithium slag geopolymer containing fly ash and silica fume

This paper investigates the thermal stability of lithium slag geopolymer (LSG) containing fly ash (FA) and silica fume (SF) exposed up to 900˚C. The effects of elevated temperatures on the microstructural evolution were investigated by thermogravimetric analysis (TGA), X-ray Diffraction (XRD), mineral analysis, surface porosity, and compressive strength of LSG modified by optimum incorporation of fly ash and silica fume. The results indicated that elevated temperature exposure significantly affects compressive strength, surface porosity, void size, weight loss, and phase transformation of fly ash incorporated lithium slag geopolymer (LSGFA) and silica fume incorporated geopolymer (LSGSF). The maximum loss in compressive strength of 44.07% was observed in LSGFA compared to 31.50% loss in LSGSF after exposure at 900˚C. The weight loss of LSGSF was higher than that of LSGFA between 500 and 800˚C and 800–1000˚C indicating a higher degree of dehydroxylation, crystal phase transformation, and viscous sintering observed in the former mix. A larger shrinkage cracking was observed in LSGSF by self-desiccation of the aluminosilicate paste matrix by dehydroxylation of mordenite molecules. Therefore, the degradation of compressive strength is governed by the combination of the crystallization of aluminosilicate gel and the formation of voids.

Photosynthetically-powered phototactic active nematic liquid crystal fluids and gels

One of the most ancient forms of life dating to ~3.5 billion years ago, cyanobacteria are highly abundant organisms that convert light into energy and motion, often within conjoined filaments and larger colonies that attract a great deal of interest but their active nematic behavior remained unexplored. Here we demonstrate how light causes a spontaneous self-assembly of two- and three-dimensional active nematic states of cyanobacterial filaments, with a plethora of topological defects. We quantify light-controlled evolutions of orientational and velocity order parameters during the transition between disordered and orientationally ordered states of photosynthetic active matter, as well as the subsequent active nematic’s fluid-gel transformation. Patterned illumination and foreign inclusions with different shapes interact with cyanobacterial active nematics in nontrivial ways while inducing interfacial boundary conditions and fractional boojum defects. Our phototactic model system promises opportunities to systematically explore fundamental properties and technological utility of the liquid crystalline active matter.

Lyotropic ionic liquid crystal gels derived from polyimidazolium hydrogen sulfate for enhanced proton conductivity

AbstractAnisotropic gels developed from polymer networks accommodating lyotropic liquid crystals are promising electrolytes but electrochemically inert polymers prevent ions from being conducted efficiently. In this work, we synthesized protic ionic liquid polymer in lyotropic ionic liquid crystal to improve proton conduction across the polymer skeleton in anisotropic gels. In situ polymerization of 1‐vinylimidazolium hydrogen sulfate ionic liquid dissolved in aqueous 1‐tetradecyl‐3‐methylimidazolium hydrogen sulfate lyotropic liquid crystal gave chemical liquid crystal gels exhibiting both dynamic order and mechanical strength. The protic ionic liquid polymer bridged the hydrogen bond chains between neighboring ionic lyotropic liquid crystal domains to give a proton conductivity of 117 mS cm−1 at 25°C. Macroscopic alignment of the liquid crystal gel achieved by mechanical shearing promoted proton conductivity to 137 mS cm−1. The macroscopically aligned liquid crystal gel acted stably in a fuel cell device, delivering a peak power density 2.95 times higher than the unaligned one. Gelation of lyotropic ionic liquid crystals with protic ionic liquid polymer provides an effective strategy to develop anisotropic gel electrolytes for electrochemical devices.

Bio‐Inspired Camouflage Skin with Photonic Crystal Structure and Size‐Confinement Effect

AbstractCamouflage skin holds immense potential for a variety of advanced applications, such as artificial intelligence, soft robotics, and flexible/wearable electronics. Currently, most existing materials for constructing camouflage skin are mainly based on inorganic materials with an inverse opal scaffold, which significantly limits their further development because of the poor mechanical properties and environmental instability. Inspired by rana slvaticas, a new type of camouflage skin based on one‐dimentional (1D) photonic crystal (PC) gel is designed and synthesized, which combines the advantages of 1D PC structures with 3D flexible gels in a single skin device. Taking advantage of the unique structures, the resulting camouflage skins demonstrated attractive properties, including excellent mechanical performance, self‐adaptive camouflage capabilities, and long‐term stability in ambient conditions. Specifically, the camouflage skin can quickly recognize and match the background by modulating the optical signals of external stimuli. The synergistic effect of the glycerol, the dodecyl glycerol itaconate (DGI), and the nano‐space structures altogether contribute to the outstanding long‐term environmental stability of the camouflage skin. Overall, by combining the bio‐inspired concept and molecular engineering strategy, camouflage skin based on PC gels is synthesized, which greatly enriched the application and development in the smart skins field.

Investigation of geotechnical and microstructure characteristics of gypsum soil using ground granulated blast-furnace slag (GGBS), fly ash, and lime

This study investigates the synergistic effects of Ground Granulated Blast-furnace Slag (GGBS), lime, and fly ash on improving the geotechnical properties of gypsum soil. Gypsum soil samples, constituting 84% of the mixture, were blended with lime and GGBS in proportions ranging from 0% to 16%. These mixtures underwent curing for 1, 7, 14, 28, 56, and 90 days. Tests and analytical techniques elucidated mechanisms responsible for strength improvements. Findings revealed that when fly ash was used alone, there was no significant increase in Uniaxial Compressive Strength (UCS). However, fly ash expedited essential pozzolanic reactions for silicate gel formation. The most substantial increase in UCS occurred in the 28-day samples, contrasting with lower gains in the 7, 14, 56, and 90-day periods. Enhanced strength in lime-GGBS-gypsum soil mixtures before 28 days was attributed to cation exchange and initial flocculation. In the 28-day specimens, increased strength was linked to ettringite crystal and silica gel growth. Microstructural analysis confirmed Ettringite (E) crystal growth within inter-crystalline and pore spaces. Cementitious compounds like CH, CSHH, CHS, CAH, and CASH displayed growth. The rearrangement of the clay mineral matrix, coupled with added sulfate, contributed to enhanced gypsum soil strength. Interestingly, decreased UCS in 56-day samples indicated increased ettringite crystal growth, resulting in reduced strength. Elemental analysis through Energy-dispersive spectroscopy (EDS) revealed shifts in Al: Si, Ca: Si, and Al: Ca ratios. The Al: Si ratio reduction confirmed the formation of more cementitious compounds in 90-day samples. Additionally, the Al: Si ratio in 28-day cured samples exhibited a significant decrease, signifying accelerated initial strength in lime and GGBS mixtures. The presence of sulfur (S) confirmed ettringite crystal formation, underscoring the intricate interplay between additives and curing durations, shedding light on mechanisms enhancing gypsum soil's geotechnical properties.

Phase Behavior and Rheological Properties of Size-Fractionated MXene (Ti3C2Tx) Dispersions.

Understanding the dispersion behavior of MXenes is interesting from a fundamental colloid science perspective and critical to enabling the fluid-phase manufacturing of MXene devices with controlled microstructures and properties. However, the polydispersity, irregular shape, and charged surfaces of MXenes result in a complex phase behavior that is difficult to predict through theoretical calculations. As two-dimensional (2D) nanomaterials, MXenes can form lyotropic liquid crystal phases, gels, and aggregates. This work aims to elucidate the effects of MXene (Ti3C2Tx) sheet size on their phase behavior and associated rheological properties. Aqueous dispersions of large sheets with an average lateral dimension of 3.0 μm, small sheets with an average lateral dimension of 0.3 μm, and a bimodal mixture of the two sizes were investigated by using cross-polarized optical microscopy and rheology. At low concentrations, the large MXene dispersions exhibited lyotropic liquid crystal behavior and extended aligned textures, but increasing concentration resulted in the formation of dense flocs. Dispersions of small sheets formed small birefringent domains with increasing concentration but lacked long-range ordering. A bimodal mixture of these sizes enabled the formation of liquid crystalline phases with extended aligned textures with less floc formation. These results provide insights into using polydispersity to tune dispersion microstructure and rheological properties that can be applied to designing dispersions for fluid-phase manufacturing methods, such as direct ink writing.

Supramolecular gels: a versatile crystallization toolbox.

Supramolecular gels are unique materials formed through the self-assembly of molecular building blocks, typically low molecular weight gelators (LMWGs), driven by non-covalent interactions. The process of crystallization within supramolecular gels has broadened the scope of the traditional gel-phase crystallization technique offering the possibility of obtaining crystals of higher quality and size. The broad structural diversity of LMWGs allows crystallization in multiple organic and aqueous solvents, favouring screening and optimization processes and the possibility to search for novel polymorphic forms. These supramolecular gels have been used for the crystallization of inorganic, small organic compounds of pharmaceutical interest, and proteins. Results have shown that these gels are not only able to produce crystals of high quality but also to influence polymorphism and physicochemical properties of the crystals, giving rise to crystals with potential new bio- and technological applications. Thus, understanding the principles of crystallization in supramolecular gels is essential for tailoring their properties and applications, ranging from drug delivery systems to composite crystals with tunable stability properties. In this review, we summarize the use of LMWG-based supramolecular gels as media to grow single crystals of a broad range of compounds.

Efficient Preparation of Homogeneous Chromogenic Glucose-responsive Photonic Crystal Gels by Magnetic Assembly Method

Efficient Preparation of Homogeneous Chromogenic Glucose-responsive Photonic Crystal Gels by Magnetic Assembly Method

Viologen-based supramolecular crystal gels: gelation kinetics and sensitivity to temperature.

Supramolecular crystal gels, a subset of molecular gels, are formed through the self-assembly of low molecular weight gelators into interconnecting crystalline fibers, creating a three-dimensional soft solid network. This study focuses on the formation and properties of viologen-based supramolecular crystalline gels. It aims to answer key questions about the tunability of network properties and the origin of these properties through in-depth analyses of the gelation kinetics triggered by thermal quenching. Experimental investigations, including UV-Vis absorption spectroscopy, rheology, microscopy and scattering measurements, contribute to a comprehensive and self-consistent understanding of the system kinetics. We confirm that viologen-based gelators crystallize by forming nanometer radius hollow tubes that assemble into micro to millimetric spherulites. We then show that crystallization follows the Avrami theory and is based on pre-existing nuclei. We also establish that the growth is interface-controlled, leading the hollow tubes to branch into spherulites with fractal structures. Finally, we demonstrate that the gel properties can be tuned depending on the quenching temperature. Lowering the temperature results in the formation of denser and smaller spherulites. In contrast, the gel's elasticity is not significantly affected by the quench temperature, leading us to hypothesize that the densification of spherulites occurs at the expense of connectivity between spherulites.

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.

Рt/SAPO-11 Catalytic Systems Differing in Acidity and Secondary Pore Structure in n-Hexadecane Hydroisomerization

SAPO-11 molecular sieve samples differing in the acid properties, crystal morphology and size, and secondary pore structure characteristics were obtained by crystallization of reaction gels with the SiO2/Al2O3 molar ratios of 0.1 and 0.3, prepared using aluminum isopropoxide or boehmite as an aluminum source. Platinum (0.5 wt %) was deposited onto the molecular sieves prepared, and the catalytic properties of the resulting samples in n-hexadecane hydroisomerization were studied. The hydrocarbon conversion on these samples varies from 76.8 to 87.7 wt %, and the isoparaffin formation selectivity, from 76.7 to 91.2 wt %.