Solutions In Organic Solvents Research Articles

Facile one‐step high‐temperature spray pyrolysis route toward metal carbide nanopowders

AbstractFine ultrahigh‐temperature ceramic (UHTC) powders have found very important applications in many fields. In this work, a facile high‐temperature spray pyrolysis (HTSP) approach is implemented for the synthesis of HfC and TaC UHTC nanopowders starting from organic solvent (e.g., ethanol or 1‐pentanol) solutions of metal precursors (HfCl4 or TaCl5). It is proposed that, during HTSP, the precursor solution droplets would continuously undergo rapid drying, thermolysis (i.e., removal of low molecular weight species such as H2, H2O, and CO), and finally in situ carbothermal reduction (CTR) process to give rise to metal carbide nanopowders. The as‐obtained materials are shown by SEM as uniform and separated nanoparticles (~90 nm), whereas TEM reveals the carbide (e.g., HfC) nanoparticles are actually even smaller (~10‐20 nm) and embedded in amorphous carbon from excess solvent decomposition. It is found that among different processing parameters, the organic solvent used and the metal precursor concentration could largely influence the formation of metal carbide. In addition, lower HTSP temperatures (≤~1500°C for HfC) only lead to oxide‐carbon mixtures while higher temperatures (≥~1650°C) promote carbide formation. The HTSP method developed in this work is simple, low‐cost and efficient, and could potentially be optimized further for future large‐scale manufacturing of ultrafine UHTC nanopowders.

Sorption of water–ethanol mixtures by poplar wood: swelling and viscoelastic behaviour

The swelling of wood upon impregnation by aqueous solutions of organic solvents is larger than swelling by pure water. This phenomenon, described as “hyperswelling”, results from specific interactions with components of the complex wood microstructure. To understand the combined effect of mixed solvents on wood properties, the specific influence of each solvent on wood biopolymers and structure must be first characterized. In this study, the effect of the impregnation of aqueous solutions of ethanol with concentrations from 0 to 100% on the physico-mechanical properties of poplar wood was investigated. For each solution, the sorption behaviour of veneer sapwood samples and the effect of sorption on wood viscoelasticity and microstructure were measured through vapour sorption gravimetry, dynamic mechanical analysis and optical microscopy monitoring. Pure water and pure ethanol showed contrasting sorption behaviour, ethanol leading to a much lower swelling and a very limited softening compared to water, despite comparable sorbed amounts. This result suggests different affinities of water and ethanol for biopolymers within wood microstructure. With mixed solutions, larger swelling and stronger variations in viscoelastic behaviour than in pure solvents were observed, confirming the synergistic effect of water/ethanol mixtures on structure and properties of wood cells. Microscopic observations evidenced that ethanol, both alone and in aqueous solutions, generates intercellular decohesion and disbonding of the different wood cell wall layers. These observations are consistent with a mechanism of partial solubilization by ethanol of lignin-related phenolic. This could lead to a release of the constraints which limit the swelling of the polysaccharide fraction of the cell wall by water. Such phenomenon is likely to be at the origin of the hyperswelling observed in mixed water/organic solvent systems.

Aggregation‐Enhanced Emission of Fluorescent‐Gemini Surfactants with High Photostability for Cell‐Membrane Imaging

Abstract In situ studies of the aggregation behavior of traditional surfactants at the liquid interface using spectroscopic methods are often significantly affected by the large volume of fluorescent groups, such as pyrene. Fluorescent‐Gemini surfactants provide an ideal solution since the fluorescent block can be designed as a spacer or a tail. In this work, we report the synthesis of a new fluorescent‐Gemini surfactant with a rigid spacer (referred to as 8‐TBT‐8). The aggregation behavior and application in cell‐membrane imaging were investigated. The unique aggregation behavior in an organic solvent and aqueous solution was studied using spectroscopy. UV–vis and photoluminescence spectra of 8‐TBT‐8 revealed that this new fluorescent surfactant forms H aggregates in organic solution to give blue emission, whereas it forms J aggregates in aqueous solution to give green fluorescence under UV light. In addition, the fluorescence intensity of 8‐TBT‐8 increases abruptly at concentrations higher than the critical micellization concentration. Good photostability and a unique structure make the synthesized Gemini surfactant very suitable for membrane imaging.

Design and Investigation of Optical Properties of N-(Rhodamine-B)-Lactam-Ethylenediamine (RhB-EDA) Fluorescent Probe.

This study presents chemical modification of a Rhodamine B (RhB) sensor probe by ethylenediamine (EDA), and investigation of its spectral as well as sensor properties to the various metals. The synthesised N-(Rhodamine-B)-lactam-ethylenediamine (RhB-EDA) fluorescent probe shows interesting optical sensor properties, and high sensitivity and selectivity to Ag+ ions among all the tested metal ions (K+, Mg2+, Cu2+, Ni2+, Fe2+, Pb2+, Na+, Mn2+, Li+, Al3+, Co2+, Hg2+, Sr2+, Ca2+, Ag+, Cd2+ and Zn2+), while the well-known Rhodamine B (RhB) fluorescent probe shows much less sensitivity to Ag+ ions, but high sensitivity to Fe2+ ions. The novel fluorescent sensor probe RhB-EDA has the capabilities to sense Ag+ ions up to µM ranges by using the fluorescence quenching approach. The probe displayed a dynamic response to Ag+ in the range of 0.43 × 10−3–10−6 M with a detection limit of 0.1 μM. The sensing system of an RhB-EDA novel fluorescent probe was optimised according to the spectral properties, effect of pH and buffer, photostability, incubation time, sensitivity, and selectivity. Since all the spectral and sensing properties were tested in green aqueous media, although many other similar sensor systems rely on organic solvent solutions, the RhB-EDA sensing probe may be a good candidate for measuring Ag+ ions in real-life applications.

Copper Plated through-Holes for 3D Electro-Thermal Systems

Three-dimensional (3D) packaging/integration of thermal devices, multi-chips, passives, sensors, electro-optics etc. is a key technical approach to optimize power density and create 3D electro-thermal systems that are optimally designed to route both thermal and electrical power. 3D electro-thermal systems are operated at high power density and temperature. These systems have to overcome the issues of high thermal-mechanical stress and poor reliability. Interconnects with plated-through holes (PTH) fabricated by using NANO3D’s eLOCOSTM process materials for thermal and mechanical management will enable the 3D electro-thermal system to withstand high thermal stress and high temperature. Low-cost electrochemical metallization was used because it drastically reduces the cost of 3D power systems by replacing costly, high-overhead metallization processes. Electroless Ni and Cu PTH. 10 mil and 20 mil PTH were fabricated in Low Temperature and High Temperature Co-fired Ceramic substrates (LTCC and HTCC, respectively). The ceramic surfaces were pre-cleaned and etched in organic solvent and alkaline solutions before an activation step. Surface activations for electroless plating were performed by using one of two methods: tin-based sensitization or silanization followed by palladium activation. A conformal barrier layer was applied to ceramic substrates via electroless plating. Nickel barrier and copper seed layers were electrolessly plated on activated LTCC substrates. Both nickel and copper readily plate inside the vias as well as on exposed surfaces. Cu PTH. Copper electroplating was performed in a suppression-based plating solution on LTCC/HTCC blanket and patterned via substrates after Ni/Cu barrier/seed layer deposition. Pulse-reverse plating in the plating solution containing two suppressors/surfactants was used to completely fill the holes and obtained a smooth copper surface (Fig. 1). The reverse-current step removes copper from the surface. Reverse-current step combined with the agitation of the plating solution are important for hole fill because it removes peaks, bulges and ridges preferentially. This eliminates buildup along the hole (via) edges that might cause the tops and bottoms to fill before the center, leaving large crevices within the via. Blanket plated substrates were analyzed in various ways post electroplating, including optical microscopy, profilometer, and adhesion testing. For Instron testing, many samples broke at the epoxy site rather than the plated copper layer. Adhesion between the copper and substrate was over 2.6 MPa. Testing Results. Thermal shock testing of NANO3D’s PTH substrates showed promising results for the adhesion of the Cu to the ceramic substrates. Only one of the samples showed obvious delamination after 500 cycles of thermal shock (Fig. 2). Of the five samples of commercial DBC used, only two alumina samples survived the 500 cycles. Both the aluminum nitride DBC showed signs of cracking in the ceramic after 200 cycles (Fig. 2). One alumina sample started showing signs of delamination around 200 cycles as well. SAM images showed the delamination in the failed samples and showed minimal delamination in a few others that was not visible under the microscope. Figure 1

Equilibrium Compositions of HF Solutions in N,N-Dimethylformamide

For HF solutions in DMF, concentration-dependent fractions of DMF molecules (α(DMF)) that remain unassociated and that enter heteroassociates (HAs) of 1 : 1, 4 : 1, and 12 : 1 molecular stoichiometries were obtained by two independent methods, namely, from an analysis of IR spectra and by calculating the material balance. The experimental way was shown to be enough exact in determining the ratio between the solvent molecules in four different states up to ~83 mol % HF. The equilibrium compositions of HF–DMF solutions were estimated over the entire range of concentrations. Starting with [HF] of ~25 mol %, more than one-half HF molecules are associated, and at [HF] of ~50–92 mol %, at least 90% of the HF molecules are associated. The equilibrium composition of HF–organic solvent (Solv) solutions in which HAs of 1 : 1, 1 : 4, and 1 : 12 molecular stoichiometries are formed, can be described by a single set of α(HF–Solv) versus concentration plots.

Thermodynamic Properties of Butyl Methacrylate Solutions in Organic Solvents

Thermodynamic Properties of Butyl Methacrylate Solutions in Organic Solvents

Enhancement of Fluorescence and Raman Scattering in Cyanine-Dye Molecules on the Surface of Silicon-Coated Silver Nanoparticles

A method of formation of a composite structure based on silver nanoparticles and a thin protective silicon film (AgNPs/Si) is developed. Enhancement of the fluorescence and Raman scattering in cyaninedye molecules deposited onto the formed nanostructure is observed. The optical properties and morphology stability of particles that are in contact with cyanine-dye solutions in organic solvents are studied. It is shown that the AgNPs/Si composite structure can be multiply used as an SERS-active surface.

Solvophobic Acceleration of a Diels–Alder Reaction in True Solutions in Organic Solvents

ABSTRACTThe rate of Diels–Alder reaction of diene 9,10‐bis(hydroxymethyl)anthracene with dienophile N‐ethylmaleimide was studied in a series of solvents with different polarity and hydrogen‐bonding ability. Enthalpies and entropies of activation were determined from the temperature dependences of the rate constants. Rate acceleration in nonaqueous protic solvents such as glycerol, propylene, and ethylene glycols was observed. In addition, enthalpy versus entropy of activation plots show a compensation pattern different from the other considered solvents, which can be linked with the solvophobic effects observed in polyhydric alcohols. However, the solvophobic acceleration was not as strong as the hydrophobic acceleration in water. Hydrogen bonding of the reactants and transition state with solvent also influences the reaction rate. The studied reaction is slightly promoted in hydrocarbon solvents in comparison with aprotic polar solvents. This was explained by hydrogen bonding of the hydroxyl groups of diene with dienophile in transition state, which requires prior breaking of the hydrogen bonds of these groups with polar solvent molecules.

Sodium-Ion Batteries (a Review)

State-of-the-art in the studies of sodium-ion batteries is discussed in comparison with their deeper developed lithium-ion analogs. The principal problem hindering the development of competitive sodium-ion batteries is the low effectiveness of the electrode materials at hand. The principal efforts in the formation of anodes for the sodium-ion batteries are reduced to the development of materials based on carbon, metals, alloys, and transition metal oxides. Cathode materials are searched among oxides (first of all, layered) and salt systems. Synthesis of electrolytes for the sodium-ion batteries is not sufficiently attended to. Nowadays it is sodium salt solutions in organic solvents that are dominated; however, polymer and solid electrolytes with sodium conductivity may be thought of as very perspective. Reference list contains 584 items.

Structural characterization of nanoparticles formed by fluorinated poly(2-oxazoline)-based polyphiles

We report on the self-assembly behavior of poly(2-methyl-2-oxazoline)–block–poly(2-octyl-2-oxazoline) comprising different terminal perfluoroalkyl fragments in aqueous solutions. As reported previously [Kaberov et al. (2017)] such polyphiles can form a plethora of nanostructures depending of the composition and on the way of preparation. Here we report, for the first time, detailed information on the internal structure of the nanoparticles resulting from the self-assembly of these copolymers. Small-angle neutron and X-ray scattering (SANS/SAXS) experiments unambiguously prove the existence of polymersomes, wormlike micelles and their aggregates in aqueous solution. It is shown that increasing content of fluorine in the poly(2-oxazoline) copolymers results in a morphological transition from bilayered or multi-layered vesicles to wormlike micelles for solutions prepared by direct dissolution.In contrast, nanoparticles prepared by dialysis of a polymer solution in a non-selective organic solvent against water are characterized by SAXS method. The internal structure of the nanoparticles could be assessed by fitting of the scattering data, revealing complex core-double shell architecture of spherical symmetry. Additionally, long range ordering is identified for all studied nanoparticles due to the crystallization of the poly(2-octyl-2-oxazoline) segments inside the nanoparticles.

3DRISM-HI-D2MSA: an improved analytic theory to compute solvent structure around hydrophobic solutes with proper treatment of solute–solvent electrostatic interactions

ABSTRACTThe 3D reference interaction site model (3DRISM) is a powerful tool to study the thermodynamic and structural properties of liquids. However, for hydrophobic solutes, the inhomogeneity of the solvent density around them poses a great challenge to the 3DRISM theory. To address this issue, we have previously introduced the hydrophobic-induced density inhomogeneity theory (HI) for purely hydrophobic solutes. To further consider the complex hydrophobic solutes containing partial charges, here we propose the D2MSA closure to incorporate the short-range and long-range interactions with the D2 closure and the mean spherical approximation, respectively. We demonstrate that our new theory can compute the solvent distributions around real hydrophobic solutes in water and complex organic solvents that agree well with the explicit solvent molecular dynamics simulations.

Aqueous Emulsions of Polysyloxane Polyblock Copolymers as a Basis for Weatherproof Protective Coatings

On the way to solving the problem of developing an ecofriendly technology for preparing hydrophobic protective coatings to replace the existing technology involving casting from polymer solutions in toxic organic solvents, amphiphilic organosilicon oligomers, promising emulsifiers for preparing aqueous emulsions of organosilicon polymers, were synthesized. The synthesized oligomers were used to obtain stable aqueous emulsions of a film-forming silicone block copolymer. The resulting emulsions can be used to form hydrophobic protective coatings on the surface of construction materials. It was shown that the contact angle of wetting depends on the specific features of the preparation of the emulsion and reaches a maximum of 134°.

Thermodynamic Aspects of Solubility and Solvation of Bioactive Bicyclic Derivatives in Organic Solvents

The solubility of eight biologically active nonaromatic compounds with a common 3-thia-1-aza-bicyclo fragment in 1-octanol and hexane was determined in the temperature range of T = 293.15–315.15 K. The solubility of the substances in alcohol is approximately 2 orders of magnitude higher than in alkane and varies within 3.0 × 10–3 to 2.1 × 10–1 and 7.1 × 10–5to 13.5 × 10–3 mol. fractions, respectively. In accordance with the structure of the substituent at the para position of the phenyl ring, the studied compounds are arranged in the following order of decreasing solubility in both solvents: methyl- > fluoro- > ethyl- > trifluoromethyl- > cyano- > acetyl-. The ideal solubility of the substances in 1-octanol, calculated from thermophysical parameters was found to correlate with the reported experimental data. The activity coefficients of the substances in saturated solutions of organic solvents are determined by the method of distribution between two liquid phases. The thermodynamic aspects of the relation...

Reversible Iodine Capture by Nonporous Pillar[6]arene Crystals.

Here we report that easily obtained per-ethylated pillar[6]arene (EtP6) is a new adsorbent for iodine capture with high chemical and thermal stability. Nonporous EtP6 solids are shown to capture not only volatile iodine in the air but also iodine dissolved in an organic solvent and aqueous solution. Uptake of iodine leads to a structural transformation of EtP6 in the solid state. In the single crystal structure of iodine-doped EtP6 (I2@EtP6), each adsorbed iodine molecule is located between two adjacent EtP6 molecules to form a linear supramolecular polymer. Iodine is released spontaneously from I2@EtP6 solids when they are immersed in cyclohexane. These EtP6 solids can be reused many times without losing iodine capture capacity.

Mn2+-ZnSe/ZnS@SiO₂ Nanoparticles for Turn-on Luminescence Thiol Detection.

Biological thiols are antioxidants essential for the prevention of disease. For example, low levels of the tripeptide glutathione are associated with heart disease, cancer, and dementia. Mn2+-doped wide bandgap semiconductor nanocrystals exhibit luminescence and magnetic properties that make them attractive for bimodal imaging. We found that these nanocrystals and silica-encapsulated nanoparticle derivatives exhibit enhanced luminescence in the presence of thiols in both organic solvent and aqueous solution. The key to using these nanocrystals as sensors is control over their surfaces. The addition of a ZnS barrier layer or shell produces more stable nanocrystals that are isolated from their surroundings, and luminescence enhancement is only observed with thinner, intermediate shells. Tunability is demonstrated with dodecanethiol and sensitivities decrease with thin, medium, and thick shells. Turn-on nanoprobe luminescence is also generated by several biological thiols, including glutathione, N-acetylcysteine, cysteine, and dithiothreitol. Nanoparticles prepared with different ZnS shell thicknesses demonstrated varying sensitivity to glutathione, which allows for the tuning of particle sensitivity without optimization. The small photoluminescence response to control amino acids and salts indicates selectivity for thiols. Preliminary magnetic measurements highlight the challenge of optimizing sensors for different imaging modalities. In this work, we assess the prospects of using these nanoparticles as luminescent turn-on thiol sensors and for MRI.

ELECTROCHEMICAL BEHAVIOUR OF ANTHRAQUINONE DYES IN NON AQUEOUS SOLVENT SOLUTION.: Part I. Medium effect on the electrochemical behaviour

The conditions under which alizarin, purpurin, carminc acid, quinalizarin and alizarin red S in the solution of several organic solvents can be electrochemically transformed are analysed. The electrochemical activity of these molecules with quinone and phenolic moieties is relatively easy detected by cyclic voltammetry. Numerous electro-reduction/oxidation processes without and with added acid or base are observed. The number, the current intensity and the peak potential of the charge transfer processes are rationalized on the basis of the homogeneous dissociation equilibriums of the phenolic-OH groups. These equilibria are significantly altered by the medium. A supporting electrolyte unexpected and important effect on the electrochemical behaviour is observed. Alkaline cation of the supporting electrolyte promotes the changes in the electrochemical behaviour by coordinating with opposite charge species. A confusion published in the literature that the electro-reduction of the hydroxyquinones proceeds only through the formation of a radical-anion and a dianion is revealed. Solvent effect is explained by the stabilization of charge species, which is related to some solvent properties (Gutmann acceptor/donor number and dielectric constant). Solvents with strong acceptor properties favour the dissociation of the phenolic-OH groups. The dissociation equilibriums of phenolic-OH groups in each solvent are confirmed by UV-vis spectra of each dye in solution. Alizarin in DMA solvent with added base shows a particular electrochemical behaviour.For alizarin/DMF system a reaction mechanism is proposed, and alternative mechanisms are suggested for other dyes.

Solvent and electrode influence on electrochemical forming of poly-Fe(III)-aminophenylporphyrin films

Fe(III)-complexes of amino-substituted tetraphenylporphyrins obtained from solutions in organic solvents: dichloromethane, ethanol, and dimethyl sulfoxide have been electropolymerized. The solvents’ effects on deposition and surface morphology of the obtained polyporphyrin film have been determined. It is only possible to obtain a polyporphyrin film from DMSO solutions through electrochemical activation of electropolymerization by a superoxide anion radical (O[Formula: see text]. The activation effect of the dissolved oxygen becomes evident in porphyrin interaction with the superoxide anion radical (O[Formula: see text] that is synthesized in DMSO thanks to the quasi-reversible redox process. The size of particles forming the film is lowest when the film is deposited from DMSO and highest when it is deposited from dichloromethane. Therefore, the ratio of polyporphyrin phase grain growth rate to the nucleation rate has the highest value when the film is deposited from dichloromethane. Such films have the most developed surfaces, while those deposited from ethanol are the smoothest. If the film is deposited on an ITO-electrode, the particles forming the surface are a little larger than in the case of deposition on Pt, which is explained by a slower nucleation on the ITO surface. FeClT([Formula: see text]-NH2Ph)P-based films obtained from ethanol and dichloromethane have negative photo-EMF values, which indicates that the [Formula: see text]-type films have semiconductor properties.

A support surface pore structure re-construction method to enhance the flux of TFC RO membrane

In this work, a support surface pore structure re-construction method was developed to enhance the flux of thin film composite (TFC) reverse osmosis (RO) membrane. With this method, an aqueous solution of a suitable organic solvent with a certain content, i.e., re-construction agent, was used to swell the support for a period of time and then the swelled support was immersed in water to complete the whole surface pore structure re-construction process. Herein, dimethylacetamide (DMAc) was employed as the organic solvent. It was shown that under proper conditions (i.e., the organic solvent content of 30% v/v, the re-constructing agent contacting time less than 10s and re-constructing agent contacting temperature of 25 ± 5°C), the support surface porosity and surface pore density increased a lot with the support surface pore size increasing slightly. The statistical results (obtained from scanning electron microscope images) showed that at the optimal condition, the support surface porosity and surface pore density increased by 92% and 89%, respectively. The results of RO membrane permselectivity obtained using 2000ppm NaCl solutions and 1.55MPa transmembrane pressure showed that the support surface pore structure re-construction method could improve the flux by 50.5% at most (an increase from 44.0 to 66.2Lm−2h−1) without sacrificing the salt rejection (all the membranes had a similar and high rejection of 99.38%). Besides, a support surface pore structure re-construction mechanism was proposed, which showed that the support surface pore structure was mainly determined by the diffusion and coalescence of re-construction agent molecules, and polymer chains mobility. This work provides a facile and effective method for preparing TFC RO membranes with high performance.

Ion exchange resin for PFAS removal and pilot test comparison to GAC

AbstractAmec Foster Wheeler and Emerging Compounds Treatment Technologies, Inc. tested pilot‐scale ex situ treatment technologies for treatment of poly‐ and perfluorinated alkyl substances (PFAS) in groundwater. The pilot test compared ion exchange resin to granular activated carbon (GAC) and evaluated in‐place regeneration of the resin to restore PFAS removal capacity. During the pilot test, both resin and GAC removed perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) below U.S. Environmental Protection Agency (USEPA) health advisories (HAs) of 0.070 micrograms per liter (μg/L) combined. Compared at a common empty bed contact time (EBCT) of five minutes, the resin treated over eight times as many bed volumes (BVs) of groundwater as GAC before PFOS exceeded the USEPA HA and six times as many BVs for PFOA. On a mass‐to‐mass basis, resin removed over four times as much total PFAS per gram as GAC before breakthrough was observed at the USEPA HA. A solution of organic solvent and brine was used to regenerate the resin in the lead vessel, which had treated water up to the point of PFOS and PFOA breakthrough exceeding the USEPA HAs. The pilot test demonstrated successful in‐place regeneration of the resin to near‐virgin conditions. The regenerated resin was then used to treat the contaminated groundwater up to the same breakthrough point. Compared to the virgin resin loading cycles, PFAS removal results for the regenerated resin were consistent with virgin resin.