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Supercritical Fluids Technologies as a Basis for Development of Innovative Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Soft Matter".

Deadline for manuscript submissions: closed (20 August 2023) | Viewed by 17030

Special Issue Editor


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Guest Editor
Institute of Solution Chemistry of the Russian Academy of Sciences, Laboratory of NMR Spectroscopy and Numerical Investigations of Liquids, Ivanovo, Russia
Interests: supercritical fluids; IR spectroscopy; NMR spectroscopy; aerogels; solubility; extraction; quantum dots; carbon dots
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Special Issue Information

Dear Colleagues,

Supercritical fluid technologies are increasingly used for the synthesis and directed modification (functionalization) of microporous materials and polymer composites needed for a wide range of applications in medicine (for example, implants and matrices for tissue engineering), pharmacy (for example, dosage forms of increased bioavailability, prolonged action and controlled release), supercapacitor elements and many other areas of science and practice. To create efficient functionalization technologies, a number of processes are used in supercritical fluids (extraction, impregnation, foaming, formation of polymeric microparticles, etc.), in which the decisive role is played by such unique properties of the SCF as the controlled density of the medium, high rates of heat and mass transfer and, at the same time, high dissolving power and zero surface tension. With all the variety of microporous materials, there are several common physical and chemical processes that determine the course of all the main stages of the process of pore formation and the functionalization of the material, and, hence, the properties of the target product; these are, first of all, the formation of xerogels, supercritical drying and the sorption of the active pharmaceutical ingredient (API).

The goal of this Special Issue is to discuss the possibility to create a unified concept for describing such processes and methods for obtaining composites in SCF fluids, which would allow the synthesis of a number of materials based on doping with compounds of porous materials having a number of practically significant properties, such as a controlled release and high solubility. We are expecting to see manuscripts containing methods of study such as IR, NMR, X-ray and Raman spectroscopy, molecular dynamics modelling, the classical density functional method, electronic microscopy, quantum chemical calculations and many other experimental and theoretical techniques.

Dr. Mikhail G. Kiselev
Guest Editor

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Keywords

  • supercritical fluids
  • xerogel
  • extraction
  • micronization
  • polymer impregnation
  • critical phenomena
  • solubility

Published Papers (3 papers)

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Research

14 pages, 4475 KiB  
Article
Viscosity Measurement of CO2–Solvent Mixtures for the Study of the Morphology and Size of Crystalline Particles Obtained Using Supercritical Antisolvent Precipitation
by Anton M. Vorobei, Mikhail O. Kostenko and Olga O. Parenago
Materials 2023, 16(18), 6151; https://doi.org/10.3390/ma16186151 - 10 Sep 2023
Cited by 2 | Viewed by 763
Abstract
The viscosity values of CO2–dimethylphormamide, chloroform, methanol, isopropanol, ethyl acetate, acetone, and dimethyl sulfoxide mixtures were measured at a pressure of 150 bar and a temperature of 313 K. The correlation of the mean size of levofloxacin hydrochloride and malonic acid [...] Read more.
The viscosity values of CO2–dimethylphormamide, chloroform, methanol, isopropanol, ethyl acetate, acetone, and dimethyl sulfoxide mixtures were measured at a pressure of 150 bar and a temperature of 313 K. The correlation of the mean size of levofloxacin hydrochloride and malonic acid particles precipitated using the SAS method with the viscosity of the used CO2–solvent mixtures is shown. The high viscosity of the mixtures leads to slower mixing of the solution and the antisolvent. Therefore, crystallization occurs at large fractions of the solvent, and as a consequence at a lower supersaturation. This causes the formation of larger particles when using more viscous solvents in SAS. Full article
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14 pages, 3537 KiB  
Article
Investigation of the Spatial Structure of Flufenamic Acid in Supercritical Carbon Dioxide Media via 2D NOESY
by Ilya A. Khodov, Konstantin V. Belov, Michael A. Krestyaninov, Alexey A. Dyshin and Michael G. Kiselev
Materials 2023, 16(4), 1524; https://doi.org/10.3390/ma16041524 - 11 Feb 2023
Cited by 7 | Viewed by 16041
Abstract
The search for new forms of already known drug compounds is an urgent problem of high relevance as more potent drugs with fewer side effects are needed. The trifluoromethyl group in flufenamic acid renders its chemical structure differently from other fenamates. This modification [...] Read more.
The search for new forms of already known drug compounds is an urgent problem of high relevance as more potent drugs with fewer side effects are needed. The trifluoromethyl group in flufenamic acid renders its chemical structure differently from other fenamates. This modification is responsible for a large number of conformational polymorphs. Therefore, flufenamic acid is a promising structural modification of well-known drug molecules. An effective approach in this field is micronization, employing “green” supercritical fluid technologies. This research raises some key questions to be answered on how to control polymorphic forms during the micronization of drug compounds. The results presented in this work demonstrate the ability of two-dimensional nuclear Overhauser effect spectroscopy to determine conformational preferences of small molecular weight drug compounds in solutions and fluids, which can be used to predict the polymorphic form during the micronization. Quantitative analysis was carried out to identify the conformational preferences of flufenamic acid molecules in dimethyl sulfoxide-d6 medium at 25 °C and 0.1 MPa, and in mixed solvent medium containing supercritical carbon dioxide at 45 °C and 9 MPa. The data presented allows predictions of the flufenamic acid conformational preferences of poorly soluble drug compounds to obtain new micronized forms. Full article
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18 pages, 17055 KiB  
Article
Molecular Mechanism of Conformational Crossover of Mefenamic Acid Molecules in scCO2
by Roman D. Oparin, Mikhail A. Krestyaninov, Dmitry V. Ivlev and Michael G. Kiselev
Materials 2023, 16(4), 1403; https://doi.org/10.3390/ma16041403 - 07 Feb 2023
Cited by 1 | Viewed by 923
Abstract
In this work, we studied conformational equilibria of molecules of mefenamic acid in its diluted solution in scCO2 under isochoric heating conditions in the temperature range of 140–210 °C along the isochore corresponding to the scCO2 density of 1.1 of its [...] Read more.
In this work, we studied conformational equilibria of molecules of mefenamic acid in its diluted solution in scCO2 under isochoric heating conditions in the temperature range of 140–210 °C along the isochore corresponding to the scCO2 density of 1.1 of its critical value. This phase diagram range totally covers the region of conformational transitions of molecules of mefenamic acid in its saturated solution in scCO2. We found that in the considered phase diagram region, the equilibrium of two conformers is realized in this solution. In the temperature range of 140–180 °C, conformer I related to the first, most stable polymorph of mefenamic acid prevails. In the temperature range of 200–210 °C, conformer II, which is related to the second metastable polymorph becomes dominant. Based on the results of quantum chemical calculations and experimental IR spectroscopy data on the mefenamic acid conformer populations, we classified this temperature-induced conformational crossover as an entropy-driven phenomenon. Full article
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