Liquids

32 pages, 4860 KiB

Open AccessReview

Effects of Dispersed Carbon Nanotubes and Emerging Supramolecular Structures on Phase Transitions in Liquid Crystals: Physico-Chemical Aspects

by Longin Lisetski, Leonid Bulavin and Nikolai Lebovka

Liquids 2023, 3(2), 246-277; https://doi.org/10.3390/liquids3020017 - 29 May 2023

Cited by 3 | Viewed by 1388

Abstract

The current state of the study of different liquid crystalline (LC) systems doped with carbon nanotubes (CNTs) is discussed. An attempt is endeavored to outline the state-of-the-art technology that has emerged after two past decades. Systematization and analysis are presented for the integration of single- and multi-walled carbon nanotubes in thermotropic (nematic, smectic, cholesteric, ferroelectric, etc.) and lyotropic LCs. Special attention is paid to the effects of alignment and supramolecular organization resulting from orientational coupling between CNTs and the LC matrix. The effects of the specific inter-molecular and inter-particle interactions and intriguing microstructural, electromagnetic, percolation, optical, and electro-optical properties are also discussed. Full article

(This article belongs to the Special Issue Nanocarbon-Liquid Systems)

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32 pages, 2789 KiB

Open AccessArticle

Determination of the Dissociation Constants (pK_a) of Eight Amines of Importance in Carbon Capture: Computational Chemistry Calculations, and Artificial Neural Network Models

by Venkata Sai Priyatham Varma Alluri, William (Hoang Chi Hieu) Nguyen and Amr Henni

Liquids 2023, 3(2), 214-245; https://doi.org/10.3390/liquids3020016 - 20 May 2023

Viewed by 1508

Abstract

This work focuses on determining the dissociation constants (pK_a) of eight amines, namely, 3-(Diethylamino) propylamine, 1,3-Diaminopentane, 3-Butoxypropylamine, 2-(Methylamino) ethanol, Bis(2-methoxyethyl) amine, α-Methylbenzylamine, 2-Aminoheptane, and 3-Amino-1-phenylbutane, within temperatures ranging from 293.15 K to 323.15 K. The thermodynamic properties of the protonated reactions were regressed from the pK_a work. In addition, the protonated order of both 3-(Diethylamino) propylamine and 1,3-Diaminopentane were determined using computational chemistry methods owing to their unsymmetrical structures. In addition to the experimental methods, the dissociation constants at the standard temperature (298.15 K) were also estimated using group functional models (paper–pencil) and computational methods. The computational methods include COSMO-RS and computational chemistry calculations. An artificial neural network (ANN) method was employed to model the data by collecting and combining the experimental properties to estimate the missing pK_a values. Although the ANN models can provide acceptable results, they depend on the availability of the data. Instead of using the experimental properties, they were generated using software such as Aspen Plus or CosmothermX. The simulated ANN model can also provide very good fits to the experimental constant values. Full article

(This article belongs to the Section Chemical Physics of Liquids)

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11 pages, 880 KiB

Open AccessArticle

Translational Dynamics of Imidazolium-Based Ionic Liquids in Acetonitrile Solutions

by Franz Demmel and William S. Howells

Liquids 2023, 3(2), 203-213; https://doi.org/10.3390/liquids3020015 - 19 Apr 2023

Viewed by 1008

Abstract

The dynamics of pure ionic liquids and solutions with acetonitrile have been investigated through quasielastic neutron scattering (QENS). The translational diffusive motion of the 1-butyl-3-methyl-imidazolium cation was revealed as a function of concentration and temperature. The diffusion coefficients obtained are in reasonably good agreement with molecular dynamics (MD) computer simulations based on a classical potential. The diffusive mobility of the cation dramatically increases when adding acetonitrile. This increase in diffusivity is directly related to a maximum in conductivity of these ionic liquid solutions and might pave the way for new design of electrolytes. The translational motions in pure ionic liquids are too slow to be resolved by our experiment. However, localized motion resembling rotation on a sphere of the measured proton signal could be identified in the pure ionic liquids. Full article

(This article belongs to the Section Molecular Liquids)

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16 pages, 3273 KiB

Open AccessArticle

Density, Excess Molar Volume and Vapor–Liquid Equilibrium Measurements at 101.3 kPa for Binary Mixtures Containing Ethyl Acetate and a Branched Alkane: Experimental Data and Modeling

by Vincent Caqueret, Kaoutar Berkalou, Jean-Louis Havet, Marie Debacq and Stéphane Vitu

Liquids 2023, 3(2), 187-202; https://doi.org/10.3390/liquids3020014 - 11 Apr 2023

Cited by 2 | Viewed by 1908

Abstract

Vapor–liquid equilibrium (VLE) and density data for binary systems of branched alkanes + ethyl acetate are scarce in the literature. In this study, the binary mixtures 3-methylpentane + ethyl acetate and 2,3-dimethylbutane + ethyl acetate were investigated. Density measurements at atmospheric pressure were performed using a vibrating tube density meter at 293.15, 298.15 and 303.15 K. Large and positive excess molar volumes were calculated and correlated using a Redlich–Kister-type equation. Isobaric VLE data at 101.3 kPa were obtained using a Gillespie-type recirculation ebulliometer. Equilibrium compositions were determined indirectly from density measurements. The experimental data were checked for consistency by means of the Fredenslund test and the Wisniak (L-W) test and were then successfully correlated using the NRTL model. The newly studied binary systems display high deviations from ideality and minimum boiling azeotropes, the coordinates of which are reported in this work. Full article

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19 pages, 4297 KiB

Open AccessArticle

Partial Denaturation of Double-Stranded DNA on Pristine Graphene under Physiological-like Conditions

by Fernando J. A. L. Cruz and José P. B. Mota

Liquids 2023, 3(2), 168-186; https://doi.org/10.3390/liquids3020013 - 30 Mar 2023

Viewed by 1594

Abstract

Interactions between DNA and graphene are paramount for a wide range of applications, such as biosensing and nanoelectronics; nonetheless, the molecular details of such interactions remain largely unexplored. We employ atomically detailed molecular dynamics simulations with an enhanced sampling technique to investigate the adsorption and mobility of double-stranded DNA along the basal plane of graphene, in an electrolytic aqueous medium. The study focuses on physiologically relevant conditions, using a buffer of [NaCl] = 134 mM. DNA physisorption is shown to be fast and irreversible, leading to deformation and partial melting of the double helix as a result of π–π stacking between the terminal nucleobases and graphene. Denaturation occurs primarily at the termini, with ensemble averaged H-bond ratios of 47.8–62%; these can, however, reach a minimum of 15%. Transition between free-energy minima occurs via a thermodynamical pathway driving the nucleic acid from a radius of gyration of 1.5 nm to 1.35 nm. Mobility along the basal plane of graphene is dominant, accounting for ~90% of all centre-of-mass translation and revealing that the DNA’s apparent diffusivity is similar to diffusion along the endohedral volume of carbon nanotubes, but one order of magnitude faster than in other 2D materials, such as BC₃ and C₃N. Full article

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Liquids, Volume 3, Issue 2 (June 2023) – 5 articles

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