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X-Ray Crystallography in Developing New Electrolyte Systems Based on Heterocyclic Anions
Published in Władysław Wieczorek, Janusz Płocharski, Designing Electrolytes for Lithium-Ion and Post-Lithium Batteries, 2021
The ability of the dicyanoimidazolate anions to form aggregated anionic subnetworks motivated broader systematic studies to search for analogous systems in which there will be lithium cations able to carry the charge in the electrolyte besides polyanions. This requires the use of an aprotic solvent with a suitable donor number that could compete with imidazolate anions for a place in the coordination sphere of the cation. The convenient choice was using polyethylene glycol dimethyl ethers (glymes) with polyether chains of different lengths (G1–G4), often tested as solvents in lithium-ion battery electrolytes, PEO, and additionally crown ethers [27, 30]. These results shed new light on the problem of the salt aggregation with heterocyclic anions and made it possible to determine the coordinating properties of dicyanoimidazolate anions toward lithium in the presence of polyglycol molecules as a solvent. Structural motifs founded in crystalline LiTDI solvates with glymes disclosed that the aggregation process progresses with a decrease in the number of available ether donor centers compared to the number of lithium cations in the direction indicated in Fig. 2.5 with an arrow. A detailed description of lithium cation environments and resultant aggregation modes for several solvates is summarized in Table 2.1.
Properties of Ultrapure Water
Published in Tadahiro Ohmi, Ultraclean Technology Handbook, 2017
The importance of mechanical cleaning was touched upon previously. Because water, in particular ultrapure water, has quite good cleaning ability even without using surfactants, mechanical cleaning with ultrapure water is an important cleaning method on the semiconductor production line. However, mechanical cleaning with ultrapure water is effective only with polar and ionic substances. It is not effective with nonpolar substances. As shown later in discussing the properties of various compounds (Table 5 on p. 11), closely related to the solvent characteristic of water are surface tension, dielectric constant, molecular weight (size and shape of molecules), bipolar moment, donor number, acceptor number, and other characteristics, but it is impossible to explain the wide-ranging solvent ability of water by a single factor. Hildebrand suggested the solubility parameter δ, which is thought to cover water solvent ability to some extent [11, 12]: () δ=(ΔHV−RTV)1/2cal⋅ cm−3
Major Classes of Conjugated Polymers and Synthetic Strategies
Published in Sam-Shajing Sun, Larry R. Dalton, Introduction to Organic Electronic and Optoelectronic Materials and Devices, 2016
The oxidative polymerization potential of pyrrole is ca. 0.7 V versus SCE, so pyrrole can be electropolymerized in both organic and aqueous solutions. Controlling the electropolymerization conditions is crucial for the preparation of high-quality PPy films. The conductivity (σ) of the as-prepared PPy films strongly depends on the nature of the solution anions, which changes from the order of 10−1 S/cm to the order of 102 S/cm for different counter anions. Generally, the anions of strong acids and the surfactant anions are favorable for the preparation of high-quality PPy films. In the aqueous solutions, flexible PPy films with σ higher than 100 S/cm can be produced with the surfactant anions such as tosylate and benzene sulphonate. The concentration of the electrolyte anions also plays an important role. Too low concentration of the anions will lead to poor PPy films. The concentration of the anions should be no lower than 0.1 M. And the concentration of pyrrole monomer is usually 0.1 M. The effect of solvent on the electropolymerization was found to be related to the donor number (DN) of the solvent [10]. The lower the DN value of the solvent, the higher the conductivity of the as-prepared PPy films (Table 6.5). Water is a special solvent in comparison with organic solvent, its acidity can be regulated by changing pH values. The optimizing pH value of the aqueous solutions for pyrrole electropolymerization is between pH 2 and 5.5. In a basic aqueous solution, conducting PPy cannot be produced. In addition to the solvent and supporting electrolyte, small amount of additives in the solutions can sometimes influence the electropolymerization. Surfactants have been proven to be the effective additives to improve the quality of the PPy films. With nonionic surfactant nonylphenol polyethyleneoxy (10) as an additive in the sodium tosylate (TsONa) aqueous solution, the tensile strength of the as-prepared PPy film reached 127 MPa, which is five times higher than that of the PPy film produced from the solution without the surfactant additive [11]. The surfactant molecules may adsorb on the surface of the electrode where PPy will deposit and change the interface structure between the electrode and the solution, which benefits the deposition of high-quality PPy films.
Extraction of Gold from Chloride Solutions Using Dibasic Esters: A Structure-Reactivity Study
Published in Solvent Extraction and Ion Exchange, 2020
Michael J. Nicol, Mmatlou P. Kganyago
In order to correlate the extraction data with the solvating properties of the extractants, the donor-acceptor approach was considered. The Donor number (DN)[13,14] was introduced as a solvent-independent representation for the donor ability of a molecule for solvation of an acceptor such as a cation. It is defined as the molar enthalpy for the reaction of the donor with SbCl5 as a reference acceptor in a 1 mM solution of 1,2-dichloroethane. This requires calorimetric experiments to determine the enthalpy of adduct formation between the esters and antimony pentachloride in 1,2-dichloroethane. This was necessary in this case as there are no published values for the DN of the esters used in this study. The DN for water is 18.0 and that for tributylphosphate is 23.7.[15] The corresponding acceptor number (AN) is determined in a different manner (not available to the authors) with hexane as the reference solvent and generally reflects on the interaction of a donor such as an anion with a solvent. The AN of water is 54.8 while that for 1,2-dichloroethane is 20.4 and for ethyl acetate it is only 9.8[15] (AN not available for esters used in this study). This paper is an attempt to relate the extraction properties of a series of related esters with their solvating properties as reflected in the Donor number.