Typical Liquids Research Articles

Superamphiphilic Silicon Wafer Surfaces and Applications for Uniform Polymer Film Fabrication

AbstractSilicon wafers have been widely used in the semiconductor industry for many decades. Over the past decades, with the development of organic optoelectronic materials, silicon‐based organic–inorganic hybrid devices have received more and more interest in fundamental and applied research. To obtain uniform organic films for hybrid devices, superamphiphilic surfaces, on which both water and oil can spread completely, show great advantages. Herein, we prepared superamphiphilic silicon wafer surfaces with contact angles (CAs) near 0° for both water and typical organic liquids. Interestingly, lateral force mode (LFM) atomic force microscopy (AFM) images indicate that the superamphiphilicity is induced by alternating hydrophilic and hydrophobic nanodomains. By making use of these superamphiphilic silicon wafer surfaces, uniform polypyrrole (PPy) films were generated in both water and cyclopentanone, providing a versatile and effective way for the integration of organic optoelectronic materials with inorganic microelectronic devices.

Electrodeposition of Al from chloroaluminate ionic liquids with different cations

Four typical chloroaluminate ionic liquids (ILs) with different cations, namely 1-butyl-3-methylimidazoliumchloride [Bmim]Cl/AlCl3 (33.3/66.7 mol%), 1-butyl-3-methylpyridinium chloride [BMPyri]Cl/AlCl3 (33.3/66.7 mol%), 1-butyl-1-methylpyrrolidiniumchloride [Py1,4]Cl/AlCl3 (33.3/66.7 mol%), and trimethylphenylammonium chloride [TMPA]Cl/AlCl3 (33.3/66.7 mol%), were employed to deposit Al. The viscosity and ionic conductivity of these ILs were measured. The results showed that [Bmim]Cl/AlCl3 (33.3/66.7 mol%) had the lowest viscosity and the highest conductivity. Raman spectra showed that Al2Cl7 − was the main anion in the four systems. Cyclic voltammetry indicated that [Bmim]Cl/AlCl3 (33.3/66.7 mol%) had the highest reduction current for Al deposition in the four ILs. By comparing the quality of the Al coatings prepared at the same current density and temperature, it was found that compact and smooth Al deposits could be obtained from [Bmim]Cl/AlCl3 (33.3/66.7 mol%) at 303 K, while the temperature needed was higher than 333 K for the other three ILs to obtain Al deposits with the same quality. Based on the density functional theory (DFT) calculations, the differences in these properties were attributed to the different molecular structure and cation-anion interaction induced by the cations of these ILs.

The features of heterogeneous water droplet evaporation in high-temperature combustion products of typical flammable liquids

This paper presents the experimental results on heating and evaporation features of heterogeneous (with opaque solid particles ? the size of 0.05-0.5 mm, relative mass concentration 0-1%) water droplets (the initial size ? radius 1-3 mm) during their motion through high-temperature (500-1800 K) gases. A significant increase in the integral characteristics of evaporation by introducing opaque inclusions into droplets was observed. The influence of energy accumulation on the conditions of droplet evaporation at the internal solid/liquid interfaces was established. For proportioned inclusions, the conditions of intensive vaporization (leading to the explosive disintegration of droplets) at internal inclusion/liquid interfaces was set. To summarize research results, experiments were conducted with the combustion products of kerosene, gasoline, industrial alcohol, acetone, and oil. The particles of graphite, carbon, and aluminum as solid inclusions were used. The investigation compared integral characteristics of heterogeneous droplet evaporation under the conditions of non-stationary (gas temperature varied from 1800 K to 500 K over the length of channel) and nearly stationary (gas temperature was maintained at about 1100 K) heating.

The errors when determining the thermophysical characteristics of liquids by the laser flash method

The analysis of errors in determining the thermophysical characteristics of typical organic liquids, specified by conductive-radiative heat transfer of ultrathin heated up to high temperature sample layer, under conditions consistent with the implementation of the laser pulse method, when exposed to the surface of the collimated laser pulse of finite duration was made. The influence to the error of the radiation absorption process was discovered.

High-Voltage and Noncorrosive Ionic Liquid Electrolyte Used in Rechargeable Aluminum Battery.

As a promising post-lithium battery, rechargeable aluminum battery has the potential to achieve a three-electron reaction with fully use of metal aluminum. Alternative electrolytes are strongly needed for further development of rechargeable aluminum batteries, because typical AlCl3-contained imidazole-based ionic liquids are moisture sensitive, corrosive, and with low oxidation voltage. In this letter, a kind of noncorrosive and water-stable ionic liquid obtained by mixing 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM]OTF) with the corresponding aluminum salt (Al(OTF)3) is studied. This ionic liquid electrolyte has a high oxidation voltage (3.25 V vs Al3+/Al) and high ionic conductivity, and a good electrochemical performance is also achieved. A new strategy, which first used corrosive AlCl3-based electrolyte to construct a suitable passageway on the Al anode for Al3+, and then use noncorrosive Al(OTF)3-based electrolyte to get stable Al/electrolyte interface, is put forward.

Structural study of lysozyme in two ionic liquids at cryogenic temperature

We have investigated the structure and activity of chicken egg-white lysozyme in aqueous solutions of two typical ionic liquids, 1-butyl-3-methylimidazolium chloride and ethylammonium nitrate, at cryogenic temperature. An increase in structural disorder due to the unfolding and a decrease in the α-helical structure of lysozyme were noticeable upon glass formation. However, a decrease in the structural stability after cooling was less than that before cooling. The secondary and tertiary structures showed good reversibility upon cooling to 77K and then reverting back to ambient temperature. We discussed an influence of a cooling upon the structure in aqueous ionic liquid solutions.

Study of the Effect of Electrolyte Concentration on Li-Air Battery Performance

Rechargeable Li-air (Li-O2) batteries have recently attracted enormous attention due to their prospective high energy density. To realize reversible and stable operation of Li-air batteries, however, many serious problems, such as volatilization of electrolyte, high charge overpotential and electrolyte decomposition by O2 - radical, have to be solved [1]. We previously reported that equimolar mixtures of glymes and Li salts behave as ionic liquids (ILs) rather than as ordinary concentrated electrolyte solutions [2]. For instance, triglyme (G3) can coordinate to a Li+ ion, forming a 1:1 solvate cation of [Li(G3)]+, which behaves as an independent cation similar to the cation of typical ionic liquids. Thus, the glyme-Li salt complex has been categorized as a new subclass of ionic liquids called “solvate ILs” [3]. Solvate ILs show negligible volatility and high oxidative stability which are important for stable operation of the Li-air battery system [4]. The concentration of Li salt in glyme-Li salt solvate ionic liquids are extremely high ~ 3 mol dm−3. In this extremely concentrated electrolyte, almost all the solvents (glyme) coordinate to Li+ cation and almost no free (uncoordinated) solvent exists, which is an unique nature of the “concentrated electrolyte” [5]. These days, highly concentrated electrolytes, including solvate ionic liquids, have been attracted much attention owing to their unique properties [6]. In this study, we investigated the relationship between solubility of the intermediate and reversibility of Li-air battery performance as a function of Li+ concentration by RRDE method. Although it has been already reported that solubility of the intermediate depends on donor number of the solvent species and affects morphology of the discharge compounds [7], our results revealed that high Li+ concentration suppresses the intermediate solubility even in high donor number solvents such as DMSO (Figure). This low intermediate solubility originates from the absence of free solvent molecules. For the dissolution of LiO2, LiO2 should be solvated. The absence of free solvent in the highly concentrated electrolytes results in insolubility of LiO2. Interestingly, reversibility of the disk electrode reaction in highly intermediate soluble electrolyte (0.1 mol dm-3 Li[TFSA]/DMSO) is much lower than that of the intermediate insoluble electrolyte (3 mol dm-3 Li[TFSA]/DMSO) (Figure) because of dissolution of the intermediate species into the electrolyte solution. Further discussion such as relationship between solubility of LiO2 and battery performance will also be discussed. Acknowledgement This study was partly supported by RISING program from the New Energy and Industrial Technology Development Organization (NEDO) of Japan.

Integral characteristics of water droplet evaporation in high-temperature combustion products of typical flammable liquids using SP and IPI methods

This paper examines the evaporation features of water droplets moving through high-temperature combustion products of typical flammable liquids (on an example of gasoline, kerosene, ethanol, and acetone). Using Shadow Photography and Interferometric Particle Imaging methods contributed to perform the given experimental research. Such approach enabled to establish the integral characteristics of droplet motion (sizes and velocities) and evaporation process (evaporation rate). The initial droplet sizes (radii) and the temperatures of combustion products varied in a wide range: 0.05–4 mm and 400–1900 K, respectively. The choice of these ranges allowed us to summarize the research results, which can be applied in a group of promising high-temperature (usually more than 1000 K) gas-vapor-droplet technologies (thermal or flame methods of liquid waste treatment; heat carriers based on flue gases, steam, and water droplets; polydisperse firefighting). Conditions of almost the complete and insignificant (with minimum change of liquid mass) droplet evaporation were determined. In addition, the integral characteristics of water droplet evaporation under non-stationary heat transfer (at a temperature of combustion products from 1900 K to 400 K) were compared with the same characteristics under nearly stationary heat transfer (at a temperature of 1100 ± 30 K). During short-time heating (less than 0.5 s), values of these parameters correlated well (deviations did not exceed 8–12%).

Isotropic rotation vs. shear relaxation in supercooled liquids with globular cage molecules.

The temperature dependence of the rotational dynamics of P4Se3 molecules in the glass-forming molecular liquid P5Se3 is studied using two-dimensional (31)P nuclear magnetic resonance spectroscopy. Unlike typical molecular glass-forming liquids, the constituent molecules in the P5Se3 liquid perform rapid isotropic rotation without significant translational diffusion in the supercooled regime and this rotational process shows a decoupling in time scale from shear relaxation by nearly six orders of magnitude at the glass transition. This dynamical behavior of liquid-like rotation and localized translation appears to be universal to glass-forming liquids with high-symmetry globular molecules that are characterized by an underlying thermodynamically stable plastic crystal phase.

The configuration exchanging theory for transport properties and glass formation temperature of ionic liquids.

Understanding molecular motion in terms of molecular structure is an important issue for microscopic understanding of the nature of transport properties and glass transition, and for design of structured materials to meet specific demands in various applications. Herein, a novel molecular mechanism is proposed to connect macroscopic motion in ionic liquids with molecular structure via conformational conversions of the constituent ions or of the cation-anion pairs. New equations for description of relaxation time, diffusion coefficient, molar conductivity, and viscosity of ionic liquids are established. The equation parameters, which were determined from the temperature dependent heat capacities, self-diffusion coefficients, molar conductivities, and viscosities of typical ionic liquids, were used to produce predictions for the corresponding properties of other ionic liquids and for the glass transition temperatures of representative ionic liquids. All predictions are in nice agreements with the experimental results.

Experimental estimation of characteristic times of the existence of liquid drops in the form of a sphere and ellipse upon their movement in a gas environment under the conditions of moderate weber numbers

The experimental procedure has been developed and studies using high-speed (105 frames per second) system of cross-correlation video registration of a change in the shape of drops for the most typical liquids that are widely used in various chemical technologies (water, kerosene, and ethyl alcohol) have been carried out. The liquids move with significantly subsonic speeds (up to 5 m/s) in the air environment under the influence of gravitational forces. The initial sizes of drops varied in the range of 3–6 mm. The cyclic nature of the changes in the shapes of drops during movement has been established. Characteristic times of transitions from one shape of drop to another have been measured. Characteristic times of the existence of drops in the form of spheres and ellipses have been defined. Recommendations about the use of geometrical models of liquid drops for theoretical study of heat and mass transfer and hydrodynamics in the course of their movement through gas environments under the conditions of moderate Weber numbers have been formulated.

Advantages and challenges in coupling an ideal gas to atomistic models in adaptive resolution simulations

In adaptive resolution simulations, molecular fluids are modeled employing different levels of resolution in different subregions of the system. When traveling from one region to the other, particles change their resolution on the fly. One of the main advantages of such approaches is the computational efficiency gained in the coarse-grained region. In this respect the best coarse-grained system to employ in the low resolution region would be the ideal gas, making intermolecular force calculations in the coarse-grained subdomain redundant. In this case, however, a smooth coupling is challenging due to the high energetic imbalance between typical liquids and a system of non-interacting particles. In the present work, we investigate this approach, using as a test case the most biologically relevant fluid, water. We demonstrate that a successful coupling of water to the ideal gas can be achieved with current adaptive resolution methods, and discuss the issues that remain to be addressed.

Properties of water confined in ionic liquids.

The varying states of water confined in the nano-domain structures of typical room temperature ionic liquids (ILs) were investigated by 1H NMR and by measurements of self-diffusion coefficients while systematically varying the IL cations and anions. The NMR peaks for water in BF4-based ILs were clearly split, indicating the presence of two discrete states of confined water (H2O and HOD). Proton and/or deuterium exchange rate among the water molecules was very slowly in the water-pocket. Notably, no significant changes were observed in the chemical shifts of the ILs. Self-diffusion coefficient results showed that water molecules exhibit a similar degree of mobility, although their diffusion rate is one order of magnitude faster than that of the IL cations and anions. These findings provide information on a completely new type of confinement, that of liquid water in soft matter.

Behaviour of zinc during the process of leaching copper from WPCBs by typical acidic ionic liquids

The leaching behavior of zinc, representing heavy metals, during the process of recycling copper in typical acidic ionic liquids from waste printed circuit boards was examined and the connection between copper and zinc during the leaching process was investigated in detail.

Correction: Behaviour of zinc during the process of leaching copper from WPCBs by typical acidic ionic liquids

Correction for ‘Behaviour of zinc during the process of leaching copper from WPCBs by typical acidic ionic liquids’ by Mengjun Chen et al., RSC Adv., 2015, 5, 34921–34926.

What is liquid? Lyapunov instability reveals symmetry-breaking irreversibilities hidden within Hamilton's many-body equations of motion

Typical Hamiltonian liquids display exponential "Lyapunov instability", also called "sensitive dependence on initial conditions". Although Hamilton's equations are thoroughly time-reversible, the forward and backward Lyapunov instabilities can differ, qualitatively. In numerical work, the expected forward/backward pairing of Lyapunov exponents is also occasionally violated. To illustrate, we consider many-body inelastic collisions in two space dimensions. Two mirror-image colliding crystallites can either bounce, or not, giving rise to a single liquid drop, or to several smaller droplets, depending upon the initial kinetic energy and the interparticle forces. The difference between the forward and backward evolutionary instabilities of these problems can be correlated with dissipation and with the Second Law of Thermodynamics. Accordingly, these asymmetric stabilities of Hamilton's equations can provide an "Arrow of Time". We illustrate these facts for two small crystallites colliding so as to make a warm liquid. We use a specially-symmetrized form of Levesque and Verlet's bit-reversible Leapfrog integrator. We analyze trajectories over millions of collisions with several equally-spaced time reversals.

The Characteristics of Water Droplet Evaporation in the Flames of Various Flammable Liquids

This paper investigates the integral characteristics of the evaporation of water droplets (the initial diameter 4–6 mm) during their motion in flames obtained through the combustion of typical flammable liquids for various purposes, such as kerosene and denatured alcohol. We performed the experiments using high-speed video cameras and panoramic cross-correlation techniques PTV and SP. The difference between evaporation rates under appropriate conditions has been defined. The influence of a droplet initial size on evaporation rate has been demonstrated.

Microscopic Structure of Naked Au Nanoparticles Synthesized in Typical Ionic Liquids by Sputter Deposition

Au nanoparticles (AuNPs) of varied sizes were synthesized in typical ionic liquids using the sputter deposition technique. Because AuNPs are dispersed freely in each ionic liquid without bonding to particular stabilizing agents, they are sometimes called “naked AuNPs”. To characterize the structure of naked AuNPs, we obtained a size distribution curve from small-angle X-ray scattering (SAXS) experiments and extracted the value of the peak position as the size of the most abundant AuNPs in each ionic liquid. The size was controlled by the type of ionic liquid and preparation temperature. To elucidate the local structure of the AuNPs in relation to their particle size, we measured the X-ray absorption fine structures (XAFS) at the Au L3-edges. The analyses of the extended XAFS revealed that the Au–Au bond lengths for AuNPs ∼1 nm in size are 2.76 to 2.81 A, in contrast with the 2.88 A bond lengths for bulk Au. Comparing our SAXS and XAFS results with previously reported theoretical studies, we conclude that ...

Low-frequency collective dynamics in deep eutectic solvents of acetamide and electrolytes: a femtosecond Raman-induced Kerr effect spectroscopic study.

In this study, we have investigated the ion concentration dependent collective dynamics in two series of deep eutectic solvent (DES) systems by femtosecond Raman-induced Kerr effect spectroscopy, as well as some physical properties, e.g., shear viscosity (η), density (ρ), and surface tension (γ). The DES systems studied here are [0.75CH3CONH2 + 0.25{f KSCN + (1 - f )NaSCN}] and [0.78CH3CONH2 + 0.22{f LiBr + (1 - f )LiNO3}] with f = 0, 0.2, 0.4, 0.6, 0.8, and 1.0. γ of these DES systems shows near insensitivity to f, while ρ shows a moderate dependence on f. Interestingly, η exhibits a strong dependence on f. In the low-frequency Kerr spectra, obtained via the Fourier transform of the collected Kerr transients, a characteristic band at ∼70 cm(-1) is clear in [0.78CH3CONH2 + 0.22{f LiBr + (1 - f )LiNO3}] DES especially at the larger f. The band is attributed to the intermolecular hydrogen bond of acetamide. Because of less depolarized Raman activities of intermolecular/interionic vibrational motions, which are mostly translational (collision-induced or interaction-induced) motions, of spherical ions, the intermolecular hydrogen-bonding band is clearly observed. In contrast, the intermolecular hydrogen-bonding band is buried in the other intermolecular/interionic vibrational motions, which includes translational and reorientational (librational) motions and their cross-terms, in [0.75CH3CONH2 + 0.25{f KSCN + (1 - f )NaSCN}] system. The first moment (M1) of the intermolecular/interionic vibrational band in these DES systems is much higher than that in typical neutral molecular liquids and shows a weak but contrasting dependence on the bulk parameter √γ/ρ. The time constants for picosecond overdamped Kerr transients in both the DES systems, which are obtained on the basis of the analysis fitted by a triexponential function, are rather insensitive to f for both the DES systems, but all the three time constants (fast: ∼1-3 ps; intermediate: ∼7-20 ps; and slow: ∼100 ps) are different between the [0.78CH3CONH2 + 0.22{f LiBr + (1 - f )LiNO3}] and [0.75CH3CONH2 + 0.25{f KSCN + (1 - f )NaSCN}] systems. These results indicate that the intermolecular/interionic interactions in DES systems is strongly influenced by the ionic species present in these DES systems.

Volatile times for the very first ionic liquid: understanding the vapor pressures and enthalpies of vaporization of ethylammonium nitrate.

A hundred years ago, Paul Walden studied ethyl ammonium nitrate (EAN), which became the first widely known ionic liquid. Although EAN has been investigated extensively, some important issues still have not been addressed; they are now tackled in this communication. By combining experimental thermogravimetric analysis with time of flight mass spectrometry (TGA-ToF-MS) and transpiration method with theoretical methods, we clarify the volatilisation of EAN from ambient to elevated temperatures. It was observed that up to 419 K, EAN evaporates as contact-ion pairs leading to very low vapour pressures of a few Pascal. Starting from 419 K, the decomposition to nitric acid and ethylamine becomes more thermodynamically favourable than proton transfer. This finding was supported by DFT calculations, which provide the free energies of all possible gas-phase species, and show that neutral molecules dominate over ion pairs above 500 K, an observation that is in nearly prefect agreement with the experimental boiling point of 513 K. This result is crucial for the ongoing practical applications of protic ionic liquids such as electrolytes for batteries and fuel cells because, in contrast to high-boiling conventional solvents, EAN exhibits no significant vapour pressure below 419 K and this property fulfils the requirements for the thermal behaviour of safe electrolytes. Overall, EAN shows the same barely measurable vapour pressures as typical aprotic ionic liquids at temperatures only 70 K lower.