Nonvolatile Liquid Research Articles

A novel capillary forces-founded accessory for reliable measurements of ATR-FTIR spectra of volatile liquids

Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy (ATR-FTIR) is one of the most commonly used IR sampling techniques. This is due to the simplicity and fastness of operation, and no need to pre-prepare samples. Furthermore, ATR is a non-destructive technique that allows the analysis of very small amounts of sample. Nevertheless, while it is easy to measure good-quality spectra of solids and non-volatile liquids, reliable ATR-FTIR analysis of volatile samples stays quite challenging so far. This is because of the changes that occur over the measurement time in the sample composition associated with its evaporation. Herein, we proposed a novel, simple accessory which makes feasible the long-time measurements of ATR-FTIR spectra of such samples. The concept is based on the capillary rise effect. Trapping the sample in the capillary minimizes its contact with the atmosphere, and therefore prevents its evaporation and possible interactions with oxygen. The tests carried out for two highly volatile mixtures (i.e. polystyrene dissolved in dichloromethane and automotive gasoline) revealed that using the developed accessory enables stabilization of the sample at an acquisition time extended for up to 40 min. This in turn allows for improving the quality of the spectra, which feature a 2.7–2.9 times higher signal-to-noise level than for the conventional measurements.

Performance of pulsed plasma thrusters with a non-volatile liquid propellant stored in porous ceramics with different pore diameters

Pulsed plasma thrusters (PPTs) typically have characteristics like a high specific impulse, a small volume, a low system mass when used in microsatellites. However, the lifetime of these thrusters is limited by their disadvantages, which include carbon deposition. A non-volatile liquid perfluoropolyether showed a good capability of lower carbon deposition in previous studies, but previous investigations focused on carbon deposition. The influence of the pore diameter of porous ceramics, which can change the supply rate, has not yet been studied. Perfluoropolyether, which is impregnated into the porous ceramics with different pore diameters (10 nm, 100 nm, 1 μm), was investigated in this study. A decreasing pore diameter of porous ceramics resulted in a lower resupply rate to reduce the ablated mass bit (the consumption of propellant per discharge) of PPTs. The use of perfluoropolyether resulted in an increase in the ablated mass bit and impulse bit, and a decrease in the specific impulse and efficiency. When using perfluoropolyether, the impulse bit increases with decreasing pore diameter of the porous ceramic. Perfluoropolyether achieved a higher specific impulse and efficiency with decreasing pore diameter of the porous ceramic, due to the increasing kinetic energy of plasma as a percentage of total energy.

Boiling of water droplet in glass–oil–water multiphase system

Boiling a volatile droplet in non-volatile liquid is complex because of various interface interactions in a solid–liquid–liquid system. Previous studies have reported explosive boiling and attributed this phenomenon to heterogeneous nucleation due to solid–liquid contact. In this study, we investigated the boiling of an approximately 2 mm-diameter water droplet in a silicon oil pool inside a glass container. Two transition temperatures were observed: 122.5 °C (for the transition from evaporation to boiling) and 160.0 °C (for the transition from the bubble growth on the oil side to that on both the oil and water sides). Moreover, four boiling modes were identified: evaporation (E), boiling in water (BIW: bubble nucleation at the glass–water interface and growth inside a drop), boiling in oil (BIO: bubble nucleation at the oil–water interface and growth in oil), and boiling in oil and water (BIOW: bubble nucleation at the oil–water interface and growth in oil and water). For the first time, boiling bifurcation was observed for drop boiling in a three-phase system. For the oil temperature (Tb) in the range 122.5–160.0 °C, the boiling mode switches between BIW and BIO. In contrast, for Tb exceeding 160.0 °C, either BIW or BIOW occurs. This bifurcation occurs because droplets prefer minimum activation energy between that for the bubble nucleation at the solid–water interface and that for the bubble nucleation at the oil–water interface. Interfacial instabilities were analyzed to explain why BIOW was more violent than BIW. This work presents a comprehensive understanding of droplet boiling in a three-phase system.

Novel Dry Spinning Process of Natural Macromolecules for Sustainable Fiber Material -1- Proof of the Concept Using Silk Fibroin.

Researchers around the world are developing technologies to minimize carbon dioxide emissions or carbon neutrality in various fields. In this study, the dry spinning of regenerated silk fibroin (RSF) was achieved as a proof of concept for a process using ionic liquids as dissolution aids and plasticizers in developing natural polymeric materials. A dry spinning equipment system combining a stainless-steel syringe and a brushless motor was built to generate fiber compacts from a dope of silk fibroin obtained by degumming silkworm silk cocoons and ionic liquid 1-hexyl-3-methyl-imidazolium chloride ([HMIM][Cl]) according to a general method. The maximum stress and maximum elongation of the RSF fibers were 159.9 MPa and 31.5%, respectively. RSF fibers containing ionic liquids have a homogeneous internal structure according to morphological investigations. Elemental analysis of fiber cross sections revealed the homogeneous distribution of nonvolatile ionic liquid [HMIM][Cl] in RSF fibers. Furthermore, the removal of ionic liquids from RSF fibers through impregnation washing with organic solvents was verified to enhance industrial applications. Tensile testing showed that the fiber strength could be maintained even after removing the ionic liquid. Thermogravimetric analysis results show that the organic solvent 1,1,1,3,3,3-hexafluoro-2-propanol is chemically coordinated to silk fibroin and, as a natural polymer, can withstand heat up to 250 °C.

Spectroscopic plasma plume study of a non-volatile liquid-fed pulsed plasma thruster

The development of small satellites weighing as little as 1 kg has accelerated along with the miniaturization of technology. However, there is still a lack of efficient micropropulsion systems at these scales. A possible solution is the pulsed plasma thruster, which has an inherently simple structure that is conducive towards miniaturization. As these thrusters were primarily developed in an era of larger satellites, there are systematic considerations that need to be taken into account. One of these is the propellant, where the conventional solid polytetrafluoroethylene (PTFE) propellant can be replaced with a non-volatile liquid perfluoropolyether (PFPE), enabling liquid-feeding approaches for propellant feeding. The physics behind the operation of a non-volatile liquid-fed pulsed plasma thruster still remains relatively unknown compared with the well-studied solid-fed archetype. We focus here on the use of emission spectroscopy to better understand the spatial distribution and temporal behavior of plasma components within a pulsed plasma thruster using non-volatile liquid PFPE. This is directly compared with solid PTFE to give us an understanding of the similarities and differences between the two propellant types. The overall results suggest that liquid PFPE may be a useful propellant in scenarios with a high thrust-to-power requirement and lower emphasis on electromagnetic acceleration. One such use-case is in coaxial or capillary discharge miniaturized pulsed plasma thrusters, where a significant portion of thrust is obtained from thermodynamic gas expansion rather than electromagnetic acceleration.

Theoretical reassessment of the first Stefan diffusion column experiment with a two-component liquid phase, consisting of a high-density volatile solvent and a low-density nonvolatile diluent

The Stefan column was designed in the 19th century to allow the experimental estimation of binary gas diffusion coefficients starting with a pure volatile liquid A placed at the bottom overlaid with a stagnant/inert gas B. A sweeping B stream was provided at the top to remove the diffused gas A. In 1959, Richardson first studied a two-component liquid mixture in the Stefan column. One of his systems, a high-density volatile liquid A (carbon tetrachloride) dissolved in a low-density nonvolatile liquid O (dibutyl phthalate), is of interest to our ongoing research efforts. He collected interfacial descent-time data in his single isothermal Stefan column experiment, and analyzed them with a diffusion transport model, which contained unnecessary assumptions and simplifications, to obtain the binary liquid diffusivity of A in O, D AO. The present study removes the major restrictions of the previous model, reanalyzing the reported data with an improved numerical diffusion model that includes realistic features of the one-dimensional transport problem and statistical information on the estimated D AO. The average ± standard deviation of D AO were 8.82E-10 ± 1.85E-15 m2/s (12 data points), with an error of −13.3% relative to the Richardson value. The new model also provides detailed insight on the diffusive transport dynamics of liquid A by predicting interfacial descent rates, instantaneous concentration profiles in the liquid phase, and the time-dependent fraction of the mass of A lost from the original solution. The model is valuable to chemical engineering researchers studying diffusion–evaporation phenomena and multicomponent distillation processes.

Imbibition of Liquids through a Paper Substrate in a Controlled Environment

Liquid spreading on open surfaces is a widely observed phenomenon. The physics of liquid spreading has become more complex when the surface is porous like paper or fabrics due to the evaporation of the liquid and swelling of the fibers. In this study, we have performed liquid imbibition experiments on paper strips in a controlled environment with and without using hydrophobic boundaries. The experimental results are compared to the existing analytical models that account for each effect separately. The existing models were found to be inaccurate in predicting the experimental results. We developed new analytical models by modifying existing models to predict the capillary rise of the liquid through the paper substrate accurately. Different effects, such as the barrier (hydrophobic boundary), evaporation, and swelling, are considered simultaneously while developing the modified models to mimic the exact practical situation for the first time. We discovered that the modified models predict the experimental results more accurately than the existing models. For cases with and without barriers, the final models considering several effects simultaneously predict the data with a maximum error range of 7 and 10%, respectively. Finally, we conducted capillary rise experiments with volatile (water) and non-volatile (silicon oil) liquids at various temperatures and under various relative humidity conditions to validate the analytical results.

DESIGN AND EVALUATION OF LIQUISOLID COMPACTS OF NEBIVOLOL HYDROCHLORIDE

Objective: The aim of this study was to investigate the potential of a liquisolid system to improve the dissolution rate and the bioavailability of nebivolol hydrochloride. Methods: Solubility of nebivolol was determined in different nonvolatile solvents to finalize the best nonvolatile vehicle having maximum solubility. The liquisolid compacts were prepared using Fujicalin as a carrier material, Aerosil 200 as a coating material, Polyethylene glycol 400 as a liquid vehicle, and Croscarmellose sodium as a super disintegrating agent. 23 full factorial design was used to optimize the formulation in which the drug concentration, PVP K 30, Excipient ratio (R), and nebivolol containing nonvolatile solvent liquid level were selected as independent variables by using design expert software. The eight liquisolid compact formulations were prepared. Nebivolol liquisolid compacts were evaluated for drug content, tablet hardness, Friability, disintegration, and dissolution. An in vivo study was carried out in male Wistar rats. Results: The solubility of nebivolol hydrochloride in polyethylene glycol 400 was found to be greater than the other nonvolatile solvents. The liquisolid system of nebivolol was formulated successfully using Fujicalin, Aerosil 200, and polyethylene glycol 400. In vitro evaluation parameters for the liquisolid compact were within the prescribed limits. It was found that optimized liquisolid tablet formulation showed higher dissolution than the marketed tablet, with 88.33±0.94 % drug release within 120 min and the drug release was more than 75 % in 30 min for nebivolol LS-3N, which is optimized. LS-3N liquisolid compacts follow the Peppas model and exhibited first-order release. Conclusion: The liquisolid compacts can be a promising alternative for the formulation of water-insoluble drug nebivolol hydrochloride with improved dissolution and bioavailability.

Tečno-čvrsti sistemi kao novi pristup razvoju formulacija i proizvodnji čvrstih farmaceutskih oblika lekova - izazovi i perspektive

Liquisolid systems are a novel, promising platform for the production of solid dosage forms with a high liquid content, i.e. dispersion of the drug in a suitable, hydrophilic, non-volatile liquid vehicle or liquid drug. This technology requires conventional, but highly porous excipients (carrier and coating material in the appropriate ratio) able to absorb/adsorb liquid medication, resulting in both good flowability and acceptable compression properties. This approach has shown great potential to improve the dissolution rate and bioavailability of poorly soluble drugs, and has been recognized as a good alternative to common, more complex and expensive techniques. A variety of applications of this simple technique have been investigated recently, including the preparation of: modified release tablets, orally disintegrating tablets, solid dosage forms with liquid herbal extracts, etc. This emerging technology has numerous advantages, and the most important are: simplicity, cost-effectiveness, applicability in large scale production and environmental friendliness. However, it is accompanied by certain challenges as well, such as limited applicability in the case of highly dosed drugs. This article aims to give a comprehensive overview of recent progress regarding the potential applications of this technology, as well as to give an insight into the new liquisolid-based techniques intending to further support its commercial applicability.

The Dermal Advanced REACH Tool (dART): A Bayesian Model for Dermal Exposure Assessment.

The dermal Advanced REACH Tool (dART) is a tier 2 exposure model for estimating dermal exposure to the hands (mg min-1) for non-volatile liquid and solid-in-liquid products. The dART builds upon the existing ART framework and describes three mass transport processes (deposition (Dhands), direct emission and direct contact (Ehands), and contact transfer (Thands)) that may each contribute to dermal exposure. The mechanistic model that underpins the dART and calibration of the mechanistic model, such that the dimensionless score that results from encoding contextual information about a task into the determinants of the dART can be converted into a prediction of exposure (mg min-1), have been described in previous work. This paper completes the methodological framework of the dART model through placing the mechanistic model within a wider statistical modelling framework. A mixed-effects model, within a Bayesian framework, is presented for modelling the rate of dermal exposure per minute of activity. The central estimate of exposure for a particular task is provided by a calibrated mechanistic model (and thus based upon contextual information about a task). The model also describes between- and within-worker sources of variability in dermal exposure, with prior distributions for variance components based upon the literature. Estimates of exposure based upon informative prior distributions may be updated using measurement data associated with the task. The dART model is demonstrated using three worked examples, where estimates are initially obtained based upon the prior distributions alone, and then refined through accommodating measurement data on the tasks.

Oil/Water Microreactor with a Core–Shell Wetting State on a SOB/OL-SHB/HL Multilevel Patterned Surface

Droplet-based microfluidics, which manipulate mini-discrete droplets on surfaces to accomplish various chromogenic/fluorescence reaction-based detections, are promising for microminiaturization of analysis systems. However, rapid droplet evaporation in unsaturated surroundings is a complex problem. In this study, we proposed an ingenious concept of generating an oil/water microreactor on a superoleophobic/oleophilic-superhydrophobic/hydrophilic (SOB/OL-SHB/HL) multilevel patterned surface. A dual droplet with a nonvolatile liquid packing layer and a volatile droplet core was formed on the surface, achieving overt evaporation attenuation of the droplet core. The wettabilities of the SOB/OL-SHB/HL surface were first investigated. In addition, due to their outstanding configurability, oil/water microreactors with different pattern shapes, diverse compositions, and scale-up array configurations were obtained in a simple way. Due to the overt evaporation attenuation, the storage times of the reactants and products were markedly prolonged. Finally, as proofs of concept, oil/water microreactors were successfully applied to detect the target ion and to construct a droplet-based pH detector. The proposed oil/water microreactor on the SOB/OL-SHB/HL surface with distinct precision, flexibility, and high throughput is important to the development of high-performance microfluidic chips used in diagnosis, environment monitoring, chemical analysis, and particle synthesis.

Electrospun cellulose fiber-reinforced UV-curable composites with tunable properties

The goal of a carbon-neutral economy urges the search for unconventional eco-friendly methods of manufacturing conventional materials, including functional composites. This study combines the best practices of cellulose dissolution, fiber production through electrospinning, and composite preparation to develop a facile method for preparing lightweight fiber-reinforced composites. The challenge in solution electrospinning is that the solvent must be immediately removed. We demonstrated an electrospinning method using the nonvolatile cellulose solvent ionic liquid 1-butyl-3-methylimidazolium acetate (BMIMAc). Fiber fusion was effectively prevented through the rapid removal of the solvent. The overall process resulted in micro-sized fibers and a porous cellulose matrix, which was further impregnated to prepare polymer composites. The removal of ionic liquid (IL) and the grafting of Si for reducing the hydrophilicity were confirmed by solid-state nuclear magnetic resonance, Fourier-transform infrared, and water contact angle analyses. Finally, strong, tough fiber-reinforced composites were fabricated through impregnation using UV-curable acrylic resin. The composite samples containing 10 wt% of cellulose fibers had a 10% higher Young’s modulus, 50% greater tensile strength, and an almost 100% higher strain at break compared with neat acrylic resin. All in all it was shown that pure cellulose fiber can be readily produced in controlled environment and used for effective reinforcement of polymer matrix.

Application of a liquisolid technique to cannabis sativa extract compacts: Effect of liquid vehicles on the dissolution enhancement and stability of cannabinoids

This work describes the application of liquisolid technique to enhance cannabinoid dissolution from Cannabis sativa L. (CS) compacts. Effects of five vehicles, namely, volatile (ethanol) and nonvolatile (caprylocaproyl macrogolglycerides, polyethylene glycol 400, oleoyl macrogolglycerides and polysorbate 20) liquids, on tablet properties, dissolution and stability were investigated. The viscid oleoresin CS extract was mixed with vehicles before being transformed into free-flowing powder by the use of microcrystalline cellulose and colloidal silica as carrier and coating materials. Liquid vehicles had a nonsignificant effect on liquid load factor of CS extract. CS liquisolid compacts had acceptable tableting properties in terms of weight variation, friability, hardness, content uniformity and disintegration time. Different vehicles affected the hardness, disintegration, and wettability of CS compacts and thus the dissolution behaviors of cannabinoids to different extents. Dissolutions of cannabinoids from CS compacts were rate-limited by the disintegration process. Liquisolid formulations using nonvolatile liquids with low polarity or high hydrophilic-lipophilic balance yielded more than 90% cannabinoid dissolution. Stability studies revealed nonsignificant changes in tablet characteristics, cannabinoid content and dissolutions of CS compacts when stored at 5 ± 3 °C for 3 months. This work presents a general concept of how to successfully formulate CS extract with cannabinoid dissolution enhancement characteristics.

Facile construction of aggregation-induced emission molecular liquids via Piers-Rubinsztajn reaction for green fluorescent ink

Solvent-free luminescent molecular liquids (LMLs), which exhibit nonvolatile fluidic nature and active optoelectronic properties, were widely used. For further development, we introduced siloxane units into AIE molecules, designed and synthesized TPE derivatives with siloxane side chains via facile Piers-Rubinsztajn reaction. The obtained AIE molecular liquids exhibit unique photophysical properties. Compared with the obtained alkyl TPE-solids, siloxane TPE show liquid state, which proves that the siloxane units have stronger liquefaction effect than alkyl. Viscosity test shows that siloxane TPE-liquids has far more lower viscosity and better fluidity than the long-chain alkyl molecular liquids in previous research. All those properties are attributed to the weak interaction between flexible molecular chains of siloxane. Besides, fluorescence test shows temperature responsiveness of siloxane TPE-liquids. We developed this low-viscosity nonvolatile AIE molecular liquid as green fluorescent ink.

High-volumetric capacitance and high-rate performance in liquid-mediated densified holey MXene film

Achieving both high-volumetric capacitance and high-rate performance in thick pseudocapacitive film materials plays a critical role in facilitating the realization of large-scale electrochemical energy storage. However, MXene (Ti3C2Tx), as a two-dimensional material with a high aspect ratio, is blocked by the industry problem of nanosheets self-stacking when assembled into dense films, which would induce extremely poor ionic mobility and significant attenuation of thick electrode performance. Herein, we create uniform in-plane nanopore defects in MXene nanosheets, and introduce nonvolatile liquids with different water contents, in which the interlaminar structure of holey MXene film can be accurately controlled by the capillary compression generated during evaporation. More importantly, the residual nonvolatile liquids effectively maintain the wettability of MXene surface, making it is easy to obtain compact pseudocapacitive film materials with pore structure connectivity, and allows ions to rapidly transport. The results demonstrate that the liquid-mediated densified holey MXene film can still present high-volumetric capacitance and high-rate performance at the actual mass loading level (>10 mg cm−2), which is of great significance for promoting the advancement of MXene materials from the theoretical elucidation to practical application.

Bioinspired Photonic Ionogels as Interactively Visual Ionic Skin with Optical and Electrical Synergy.

With the ever-growing demands for flexible smart interactive electronics, it remains highly desirable yet challenging to design and fabricate interactive ionic skin with multiple signal synergistic outputs. Herein, high-performance photonic ionogels (PIGs) with excellent stability and synergy sensitivity are designed by locking a non-volatile and non-hygroscopic ionic liquid (IL), that is, 1-ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)imide ([EMIm][TFSI]), into photonic elastomers based on polymer networks of poly(ethylene glycol) phenyl ether acrylate (PEGPEA). Through manipulating the degree of crosslinking, PIGs exhibit high sensitivity that can output distinct and intuitive color change in visual with the mechanochromic sensitivity of ≈1.76nm per percent strain and clear electrical signal with the gauge factor of 1, in response to a tiny stretch of millimeter scale. Thanks to the stable photonic elastomers and IL employed, the PIGs developed in this study exhibit good performance under harsh and complex environmental conditions, including high/low temperature (from -35 °C to 100 °C), dry/wet air, and high vacuum. This study provides a novel strategy for developing integrated, stable, and multifunctional photonic ionogels for ionic skin sensors and flexible interactive devices with synergistically optical and electrical output.

In-Situ One-Step Direct Loading of Agents in Poly(acrylic acid) Coating Deposited by Aerosol-Assisted Open-Air Plasma.

In biomaterials and biotechnology, coatings loaded with bioactive agents are used to trigger biological responses by acting as drug release platforms and modulating surface properties. In this work, direct deposition of poly(acrylic acid) coatings containing various agents, such as dyes, fluorescent molecules, was achieved by aerosol-assisted open-air plasma. Using an original precursors injection strategy, an acrylic acid aerosol was loaded with an aqueous aerosol and deposited on silicon wafers. Results clearly showed that agents dissolved in the aqueous aerosol were successfully entrapped in the final coating. The effect of aerosols concentration, flow rate, and treatment time, on the coating morphology and the amount of entrapped agents, was also investigated. It was demonstrated that this process has the potential to entrap a tunable amount of any sensible water-soluble agent without altering its activity. To the best of our knowledge, this is the first time that the loading of an aqueous aerosol in coatings deposited by plasma from a liquid aerosol precursor is reported. This innovative approach complements plasma deposition of coatings loaded with bioactive agents from aqueous aerosols with the use of non-volatile liquid precursors.

Controlling cross‐contamination by food allergens

Controlling cross‐contamination by food allergens

Levitation and Self-Organization of Droplets

We review studies of levitating droplets over liquid–gas interfaces and dry solid surfaces with a focus on the physical mechanisms of levitation under different conditions. A fascinating physical phenomenon of self-organization of levitating droplets into large arrays is described and explanations for this unusual behavior are reviewed. Closely related topics of nonisothermal flotation and levitation of evaporating droplets over a pool of nonvolatile liquid, as well as recent advances in the study of the Leidenfrost effect, are also discussed.

Aerodynamic and impact thresholds for cohesive mixture of sand and non-volatile liquid

The moisture has been recognized to have a significant influence on the initiation movement of sand by wind and consequently on sand transport rates. The pertinent literature regarding these phenomena is sparse and current available theoretical and empirical models exhibit considerable disagreement regarding the magnitude of moisture effects. We believe that these discrepancies comes from the fact that the moisture levels are not well controlled neither properly measured and are susceptible to strongly vary over time due to evaporation. To get rid of the variability of moisture content due to evaporation, we propose a new approach based on the use of non-volatile liquid, namely silicon oil instead of water. This insures a proper control of the liquid content and the production of reliable data concerning the variation of the transport threshold with liquid content.