Influence of the Molecular Structure of Constituents and Liquid Phase Non-Ideality on the Viscosity of Deep Eutectic Solvents

Hydrophobic deep eutectic solvents (DES) have recently been used as green alternatives to conventional solvents in several applications. In addition to their tunable melting temperature, the viscosity of DES can be optimized by selecting the constituents and molar ratio. This study examined the viscosity of 14 eutectic systems formed by natural substances over a wide range of temperatures and compositions. The eutectic systems in this study were classified as ideal or non-ideal based on their solid–liquid equilibria (SLE) data found in the literature. The eutectic systems containing constituents with cyclohexyl rings were considerably more viscous than those containing linear or phenyl constituents. Moreover, the viscosity of non-ideal eutectic systems was higher than that of ideal eutectic systems because of the strong intermolecular interactions in the liquid solution. At temperatures considerably lower than the melting temperature of the pure constituents, non-ideal and ideal eutectic systems with cyclohexyl constituents exhibited considerably high viscosity, justifying the kinetic limitations in crystallization observed in these systems. Overall, understanding the correlation between the molecular structure of constituents, SLE, and the viscosity of the eutectic systems will help in designing new, low-viscosity DES.

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Proppant Placement Using Alternate-Slug Fracturing

SPE Journal ◽

10.2118/163851-pa ◽

2014 ◽

Vol 19 (05) ◽

pp. 974-985 ◽

Cited By ~ 16

Author(s):

Sahil Malhotra ◽

Eric R. Lehman ◽

Mukul M. Sharma

Keyword(s):

High Viscosity ◽

Mixing Zone ◽

Proppant Transport ◽

Fracture Length ◽

The Past ◽

Low Viscosity ◽

Viscous Fingers ◽

Wide Range ◽

Design Calculations ◽

Viscosity Fluid

Summary New fracturing techniques, such as hybrid fracturing (Sharma et al. 2004), reverse-hybrid fracturing (Liu et al. 2007), and channel (HiWAY) fracturing (Gillard et al. 2010), have been deployed over the past few years to effectively place proppant in fractures. The goal of these methods is to increase the conductivity in the proppant pack, providing highly conductive paths for hydrocarbons to flow from the reservoir to the wellbore. This paper presents an experimental study on proppant placement by use of a new method of fracturing, referred to as alternate-slug fracturing. The method involves an alternate injection of low-viscosity and high-viscosity fluids, with proppant carried by the low-viscosity fluid. Alternate-slug fracturing ensures a deeper placement of proppant through two primary mechanisms: (i) proppant transport in viscous fingers, formed by the low-viscosity fluid, and (ii) an increase in drag force in the polymer slug, leading to better entrainment and displacement of any proppant banks that may have formed. Both these effects lead to longer propped-fracture length and better vertical placement of proppant in the fracture. In addition, the method offers lower polymer costs, lower pumping horsepower, smaller fracture widths, better control of fluid leakoff, less risk of tip screenouts, and less gel damage compared with conventional gel fracture treatments. Experiments are conducted in simulated fractures (slot cells) with fluids of different viscosity, with proppant being carried by the low-viscosity fluid. It is shown that viscous fingers of low-viscosity fluid and viscous sweeps by the high-viscosity fluid lead to a deeper placement of proppant. Experiments are also conducted to demonstrate slickwater fracturing, hybrid fracturing, and reverse-hybrid fracturing. Comparison shows that alternate-slug fracturing leads to the deepest and most-uniform placement of proppant inside the fracture. Experiments are also conducted to study the mixing of fluids over a wide range of viscosity ratios. Data are presented to show that the finger velocities and mixing-zone velocities increase with viscosity ratio up to viscosity ratios of approximately 350. However, at higher viscosity ratios, the velocities plateau, signifying no further effect of viscosity contrast on the growth of fingers and mixing zone. The data are an integral part of design calculations for alternate-slug-fracturing treatments.

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New information about the mechanism of oil displacement from productive reservoirs using flow control technologies

E3S Web of Conferences ◽

10.1051/e3sconf/202017701012 ◽

2020 ◽

Vol 177 ◽

pp. 01012

Author(s):

Rustam Mukhametshin ◽

Gulnara Kvon

Keyword(s):

Oil Recovery ◽

Experimental Studies ◽

High Water ◽

High Viscosity ◽

Oil Displacement ◽

Low Viscosity ◽

Stage Of Development ◽

Wide Range ◽

Production Wells ◽

Control Technologies

The article is devoted to improving the efficiency of methods application to increase oil recovery of deposits that are at the final stage of development. This stage is characterized by a high degree of waterlogging of reservoirs and extracted products. From a wide range of chemical methods for increasing oil recovery in Russian oil deposits, flow-regulating (flow-deflecting) technologies have become widespread. The article analyzes the results of purposeful use of thickened water for the completion of reserves of already flooded sandstone layers. Experimental studies were performed on two specially created five-point elements in the experimental sections of the Romashkinskoye deposit. To monitor the process of low-viscosity and high-viscosity oil displacement the following methods were used: a) intake, monitoring and production wells, in which the interval of productive horizons are lined with fiberglass pipes; b) method of high-frequency resistivity (technology of "VNIIneftepromgeophysics" Institute). The studies performed in the monitoring mode showed that, along with the increase in reservoir coverage by flooding at the macro level, there is also a displacement of part of the capillary-trapped oil in the already flooded layers’ intervals, that is, at the level of micro-uniformity of the porous medium. The paper concludes on the effectiveness of using flow-regulating technologies in conditions of high water availability of development objects.

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3D Printing of a Reactive Hydrogel Bio-Ink Using a Static Mixing Tool

Polymers ◽

10.3390/polym12091986 ◽

2020 ◽

Vol 12 (9) ◽

pp. 1986 ◽

Cited By ~ 1

Author(s):

María Puertas-Bartolomé ◽

Małgorzata K. Włodarczyk-Biegun ◽

Aránzazu del Campo ◽

Blanca Vázquez-Lasa ◽

Julio San Román

Keyword(s):

3D Printing ◽

Viscosity Solutions ◽

Structural Integrity ◽

Cell Types ◽

High Viscosity ◽

Soft Tissue Regeneration ◽

Low Viscosity ◽

Good Shape ◽

Wide Range

Hydrogel-based bio-inks have recently attracted more attention for 3D printing applications in tissue engineering due to their remarkable intrinsic properties, such as a cell supporting environment. However, their usually weak mechanical properties lead to poor printability and low stability of the obtained structures. To obtain good shape fidelity, current approaches based on extrusion printing use high viscosity solutions, which can compromise cell viability. This paper presents a novel bio-printing methodology based on a dual-syringe system with a static mixing tool that allows in situ crosslinking of a two-component hydrogel-based ink in the presence of living cells. The reactive hydrogel system consists of carboxymethyl chitosan (CMCh) and partially oxidized hyaluronic acid (HAox) that undergo fast self-covalent crosslinking via Schiff base formation. This new approach allows us to use low viscosity solutions since in situ gelation provides the appropriate structural integrity to maintain the printed shape. The proposed bio-ink formulation was optimized to match crosslinking kinetics with the printing process and multi-layered 3D bio-printed scaffolds were successfully obtained. Printed scaffolds showed moderate swelling, good biocompatibility with embedded cells, and were mechanically stable after 14 days of the cell culture. We envision that this straightforward, powerful, and generalizable printing approach can be used for a wide range of materials, growth factors, or cell types, to be employed for soft tissue regeneration.

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Design of Deep Eutectic Systems: A Simple Approach for Preselecting Eutectic Mixture Constituents

Molecules ◽

10.3390/molecules25051077 ◽

2020 ◽

Vol 25 (5) ◽

pp. 1077 ◽

Cited By ~ 9

Author(s):

Ahmad Alhadid ◽

Liudmila Mokrushina ◽

Mirjana Minceva

Keyword(s):

Binary Systems ◽

Eutectic Temperature ◽

Eutectic Mixture ◽

Deep Eutectic Solvents ◽

Simple Approach ◽

Molecular Structures ◽

Melting Enthalpy ◽

Wide Range ◽

Eutectic Systems ◽

Melting Entropy

Eutectic systems offer a wide range of new (green) designer solvents for diverse applications. However, due to the large pool of possible compounds, selecting compounds that form eutectic systems is not straightforward. In this study, a simple approach for preselecting possible candidates from a pool of substances sharing the same chemical functionality was presented. First, the melting entropy of single compounds was correlated with their molecular structure to calculate their melting enthalpy. Subsequently, the eutectic temperature of the screened binary systems was qualitatively predicted, and the systems were ordered according to the depth of the eutectic temperature. The approach was demonstrated for six hydrophobic eutectic systems composed of L-menthol and monocarboxylic acids with linear and cyclic structures. It was found that the melting entropy of compounds sharing the same functionality could be well correlated with their molecular structures. As a result, when the two acids had a similar melting temperature, the melting enthalpy of a rigid acid was found to be lower than that of a flexible acid. It was demonstrated that compounds with more rigid molecular structures could form deeper eutectics. The proposed approach could decrease the experimental efforts required to design deep eutectic solvents, particularly when the melting enthalpy of pure components is not available.

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Properties of Therapeutic Deep Eutectic Solvents of l-Arginine and Ethambutol for Tuberculosis Treatment

Molecules ◽

10.3390/molecules24010055 ◽

2018 ◽

Vol 24 (1) ◽

pp. 55 ◽

Cited By ~ 11

Author(s):

Filipa Santos ◽

Maria P.S. Leitão ◽

Ana C. Duarte

Keyword(s):

Deep Eutectic Solvents ◽

Liquid Solution ◽

Molar Ratio ◽

Resonance Spectroscopy ◽

Eutectic System ◽

Secondary Effects ◽

Scanning Calorimetry ◽

1H And 13C Nmr ◽

Model Cell ◽

Phosphate Buffered Saline

The treatment for tuberculosis infection usually involves a prolonged regimen of multiple antibacterial drugs, which might lead to various secondary effects. For preventing drug resistance and side-effects of anti-tuberculosis drugs, new methods for improving the bioavailability of APIs were investigated. The strategy proposed consists of the preparation of therapeutic deep eutectic solvents (THEDES), that incorporate l-arginine and ethambutol. The eutectic mixtures were prepared by mixing the components at a certain molar ratio, until a clear liquid solution was formed. The prepared mixtures were characterized by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and nuclear magnetic resonance spectroscopy (1H and 13C-NMR). The solubility and permeability of the drugs when they are in the THEDES form was evaluated at 37 °C, in phosphate buffered saline (PBS). Solubility studies showed an increase of the solubility of ethambutol when incorporated in the eutectic system. The cytotoxicity was evaluated using a model cell line (Caco-2), comparing the cytotoxicity of the API incorporated in the eutectic system. We observed that the cell viability in the THEDES was affected by the presence of citric acid, and higher cytotoxicity values were observed. Nonetheless, these findings do not compromise the possibility to use these systems as new delivery systems for ethambutol and arginine.

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Green Valorization of Olive Leaves to Produce Polyphenol-Enriched Extracts Using an Environmentally Benign Deep Eutectic Solvent

AgriEngineering ◽

10.3390/agriengineering2020014 ◽

2020 ◽

Vol 2 (2) ◽

pp. 226-239 ◽

Cited By ~ 2

Author(s):

Olga Kaltsa ◽

Spyros Grigorakis ◽

Achillia Lakka ◽

Eleni Bozinou ◽

Stavros Lalas ◽

...

Keyword(s):

High Performance ◽

Deep Eutectic Solvent ◽

Deep Eutectic Solvents ◽

Process Variable ◽

Molar Ratio ◽

Olive Leaves ◽

Total Polyphenol ◽

Solid Ratio ◽

Wide Range ◽

Efficient Recovery

Olive leaves (OLL) are considered to be a highly appreciated bioresource of bioactive polyphenolic phytochemicals, embracing several different structures. However, extraction processes based on deep eutectic solvents (DES) are very limited despite the wide range of techniques developed for the efficient recovery of polyphenols. This study had as objective the development of a simple, green, high-performance extraction methodology for OLL polyphenols, using a recently reported effective DES, composed of L-lactic acid and glycine. Initially, a screening was performed to select the most appropriate L-lactic/glycine molar ratio and process optimization was then carried out with response surface methodology. The optimized process variable values were DES/water (78% w/v), liquid-to-solid ratio of 36 mL g−1, and stirring speed of 500 rounds per minute, and the total polyphenol yield amounted to 97.53 ± 3.54 mg gallic acid equivalents per g dry matter. Extraction with DES at 80 °C did not significantly increase the total polyphenol yield, but it did enhance the total flavonoid yield and antioxidant activity. High-performance liquid chromatography analyses revealed that extraction with the DES resulted in extended oleuropein hydrolysis, to the favor of hydroxytyrosol formation. This finding might have a prospect in using properly tuned DES for polyphenol modification with improved bioactivities.

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Eutectics: formation, properties, and applications

Chemical Society Reviews ◽

10.1039/d1cs00404b ◽

2021 ◽

Author(s):

Dongkun Yu ◽

Zhimin Xue ◽

Tiancheng Mu

Keyword(s):

Deep Eutectic Solvents ◽

Eutectic Systems

Various eutectic systems including eutectic metals, eutectic salts, and deep eutectic solvents have been proposed and applied in engineering, energy and environmental fields.

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A Low-Viscosity BisGMA Derivative for Resin Composites: Synthesis, Characterization, and Evaluation of Its Rheological Properties

Materials ◽

10.3390/ma14020338 ◽

2021 ◽

Vol 14 (2) ◽

pp. 338

Author(s):

Ali Alrahlah ◽

Abdel-Basit Al-Odayni ◽

Haifa Fahad Al-Mutairi ◽

Bashaer Mousa Almousa ◽

Faisal S. Alsubaie ◽

...

Keyword(s):

Substantial Reduction ◽

Triethylene Glycol ◽

High Viscosity ◽

Resin Matrix ◽

Resonance Spectroscopy ◽

Dental Resin ◽

Triethylene Glycol Dimethacrylate ◽

Oh Groups ◽

Low Viscosity ◽

13C Nuclear Magnetic Resonance

This study aimed to synthesize new bisphenol A-glycidyl methacrylate (BisGMA) derivatives, targeting a reduction in its viscosity by substituting one of its OH groups, the leading cause of its high viscosity, with a chlorine atom. Hence, this monochloro-BisGMA (mCl-BisGMA) monomer was synthesized by Appel reaction procedure, and its structure was confirmed using Fourier transform infrared spectroscopy, 1H and 13C-nuclear magnetic resonance spectroscopy, and mass spectroscopy. The viscosity of mCl-BisGMA (8.3 Pa·s) was measured under rheometry conditions, and it was found to be more than 65-fold lower than that of BisGMA (566.1 Pa·s) at 25 °C. For the assessment of the viscosity changes of model resins in the presence of mCl-BisGMA, a series of resin matrices, in which, besides BisGMA, 50 wt % was triethylene glycol dimethacrylate, were prepared and evaluated at 20, 25, and 35 °C. Thus, BisGMA was incrementally replaced by 25% mCl-BisGMA to obtain TBC0, TBC25, TBC50, TBC75, and TBC100 blends. The viscosity decreased with temperature, and the mCl-BisGMA content in the resin mixture increased. The substantial reduction in the viscosity value of mCl-BisGMA compared with that of BisGMA may imply its potential use as a dental resin matrix, either alone or in combination with traditional monomers. However, the various properties of mCl-BisGMA-containing matrices should be evaluated.

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A Conceptional Approach of Resin-Transfer-Molding to Rosin-Sourced Epoxy Matrix Green Composites

Aerospace ◽

10.3390/aerospace8010005 ◽

2020 ◽

Vol 8 (1) ◽

pp. 5

Author(s):

Sicong Yu ◽

Xufeng Zhang ◽

Xiaoling Liu ◽

Chris Rudd ◽

Xiaosu Yi

Keyword(s):

Composite Laminates ◽

Resin Transfer Molding ◽

High Viscosity ◽

Ramie Fiber ◽

Liquid Composite Molding ◽

Curing Agent ◽

Molding Process ◽

Transfer Molding ◽

Low Viscosity ◽

Composite Molding

In this concept-proof study, a preform-based RTM (Resin Transfer Molding) process is presented that is characterized by first pre-loading the solid curing agent onto the preform, and then injecting the liquid nonreactive resin with an intrinsically low viscosity into the mold to infiltrate and wet the pre-loaded preform. The separation of resin and hardener helped to process inherently high viscosity resins in a convenient way. Rosin-sourced, anhydrite-cured epoxies that would normally be regarded as unsuited to liquid composite molding, were thus processed. Rheological tests revealed that by separating the anhydrite curing agent from a formulated RTM resin system, the remaining epoxy liquid had its flowtime extended. C-scan and glass transition temperature tests showed that the preform pre-loaded with anhydrite was fully infiltrated and wetted by the liquid epoxy, and the two components were diffused and dissolved with each other, and finally, well reacted and cured. Composite laminates made via this approach exhibited roughly comparable quality and mechanical properties with prepreg controls via autoclave or compression molding, respectively. These findings were verified for both carbon and ramie fiber composites.

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