Propylene carbonate structure

FIGURE 2.29 Snapshots and distribution of PC molecules and electrolytes along the pore width, (a) Pure PC and (b) Et4NBp4-PC solution corresponding to 0.5 M bulk solution. The coordinate z along the pore width is shown by an arrow. (Reprinted with permission from Takana, A. et al. 2010. Effect of a quaternary ammonium salt on propylene carbonate structure in slit-shape carbon nanopores. Journal of the American Chemical Society 132 2112-2113. Copyright 2010 American Chemical Society.)... 

The structure and composition of the lithium surface layers in carbonate-based electrolytes have been studied extensively by many investigators [19-37], High reactivity of propylene carbonate (PC) to the bare lithium metal is expected, since its reduction on an ideal polarizable electrode takes place at much more positive potentials compared with THF and 2Me-THF [18]. Thevenin and Muller [29] found that the surface layer in LiC104/PC electrolyte is a mixture of solid Li2C03 and a... 

Although less common than zinc chlorides, there has been much synthetic and structural work carried out on zinc bromide and iodide complexes. For example, the 1 1 adduct of N,N,N, A -tetramethyl-o-phenylenediamine with zinc bromide has been structurally characterized.630 The ion exchange properties of zinc bromide and iodide have been studied in ethylene glycol.631 The electrolytic behavior of zinc bromide in propylene carbonate has been studied and the conductance data shows the existence of dimers.632... 

Use of the tripodal ligand Saltren creates a tetranuclear complex [Mn402(Sal-tren)2][MnCl4] 2CH3CN (172) having a fused open cubane structure without a carboxylate group. At 300 K the value of the effective magnetic moment for (172) is 5.1 /Ub, which decreases to 2.0 /iB at 4.2 K. The redox properties of (172) in propylene carbonate have been studied by cyclic voltammetry. Two oxidation responses are observed at = —0.32V and 0.43 V vs. SCE. 

Du L, Qu B, Meng Y, Zhu Q (2006) Structural characterization and thermal and mechanical properties of poly (propylene carbonate)/MgAl-LDH exfoliation nanocomposite via solution intercalation. Compos Sci Technol 66 913-918... 

The edl structure of a Cd-Ga (0.3 atom % Cd) liquid electrode in aqueous [20, 21], methanol, and propylene carbonate (PC) [21, 22] solutions with inactive electrolyte (LiCl04, liBF4) was investigated. The double layer at the liquid Cd-Ga alloy differs from that of a Ga electrode, and was virtually identical with edl at the Cd electrode. 

Silver-Silver Ion Electrode This is the most popular reference electrode used in non-aqueous solutions. Since Pleskov employed it in acetonitrile (AN) in 1948, it has been used in a variety of solvents. It has a structure as shown in Fig. 6.1(a) and is easy to construct. Its potential is usually reproducible within 5 mV, if it is prepared freshly using pure solvent and electrolyte. The stability of the potential, however, is not always good enough. The potential is stable in AN, because Ag+ is strongly solvated in it. In propylene carbonate (PC) and nitromethane (NM), however, Ag+ is solvated only weakly and the potential is easily influenced by the presence of trace water and other impurities. In dimethylformamide (DMF), on the other hand, Ag+ is slowly reduced to Ag°, causing a gradual potential shift to the negative direction.2) This shift can reach several tens of millivolts after a few days. 

One difference in behavior between the hydrophilic alkali halides and hydrophobic solutes like the larger tetraalkylammonium halides in water is expressed by the enthalpy. The enthalpies of solution of the larger tetraalkylammonium halides in water are more exothermic than those of the corresponding alkali halides but in other solvents, e.g., several amides, propylene carbonate (PC), and dimethylsulfoxide (DMSO), the reverse is true. Generally, this phenomenon is attributed to an enhanced hydrogen bonding in the highly structured solvent water in the vicinity of the tetraalkylammonium ions (hydrophobic hydration) (i). This idea is substantiated by the absence of the effect in solvents like N,N-dimethylformamide (DMF), PC, and DMSO (2), where specific structural effects are not present in the pure solvents. 

When reacting either ethylene carbonate or propylene carbonate with an aliphatic diamine, a polyurethane can be produced (Figure 2.14). Polyethylene ether carbonate) diols (Harris et al., 1990), when fabricated into polyurethanes using MDI and BDO, produce elastomers that have polyester polyol features. This was shown using 13C NMR. The structure gives rise to potential for a very high virtual cross-linking density. These carbonate-derived polyesters have superior hydrolysis resistance compared to the traditional materials. 

Under certain conditions of propylene/carbon monoxide copolymerisation with certain catalysts, poly(spiroketal) structural units... 

Different mechanistic interpretations of the formation of an alternating propylene/carbon monoxide copolymer of poly(spiroketal) structure were considered [107, 478, 480, 481, 489]. Any reasonable proposal, however, needs to take into account the nature of the end groups in the copolymer chains. To date this has not been possible owing to the low solubility of the copolymer in solvents other than hexafluoroisopropanol however, this solvent, probably because of its acidic nature, causes transformation of the poly(spiroketal) structure into an isomeric poly(ketone) structure [489]. The formation of a cyclic polymeric structure could be favoured by minor entropy loss due to the intramolecularity of the process [480,481] and by the peculiar conformational situation of the poly(ketone) structure [491]. 

Under most conditions, only the simple polypropylene ketone) is formed in propylene/carbon monoxide alternating copolymerisation. Isomerisation of poly(ketone) to poly(spiroketal) can occur, and it may be assisted by cationic palladium species and protonic acids. It must be emphasised that a low reaction temperature favours the formation of a spiroketal structure [107]. At a temperature above the ceiling temperature, the poly(spiroketal) depolymerises to the more flexible and entropically favoured poly (ketone) [481]. 

The second lithium primary cell is the Li-Mn02 [18]. For use in lithium cells, the high purity EMD must be heat treated at 350°C-375°C to activate and modify the crystal structure, as well as remove any water. Carbon black is used as a conductive diluent in the cathode. The cell electrolyte is propylene carbonate and 1,2-dimethoxyethane with LiAsF6. The cell reaction is... 

Several efforts have been made to develop general rules for the induction of CD in the absorption bands of achiral compounds. Hayward was able to correlate the CD induced in the n->7r transition of a series of 30 oxyketones and thioketones (when these were dissolved in (S)-propylene carbonate) with the structures of these solutes [18],... 

Interface between two liquid solvents — Two liquid solvents can be miscible (e.g., water and ethanol) partially miscible (e.g., water and propylene carbonate), or immiscible (e.g., water and nitrobenzene). Mutual miscibility of the two solvents is connected with the energy of interaction between the solvent molecules, which also determines the width of the phase boundary where the composition varies (Figure) [i]. Molecular dynamic simulation [ii], neutron reflection [iii], vibrational sum frequency spectroscopy [iv], and synchrotron X-ray reflectivity [v] studies have demonstrated that the width of the boundary between two immiscible solvents comprises a contribution from thermally excited capillary waves and intrinsic interfacial structure. Computer calculations and experimental data support the view that the interface between two solvents of very low miscibility is molecularly sharp but with rough protrusions of one solvent into the other (capillary waves), while increasing solvent miscibility leads to the formation of a mixed solvent layer (Figure). In the presence of an electrolyte in both solvent phases, an electrical potential difference can be established at the interface. In the case of two electrolytes with different but constant composition and dissolved in the same solvent, a liquid junction potential is temporarily formed. Equilibrium partition of ions at the - interface between two immiscible electrolyte solutions gives rise to the ion transfer potential, or to the distribution potential, which can be described by the equivalent two-phase Nernst relationship. See also - ion transfer at liquid-liquid interfaces. 

The surface film on such lithium particles have been analyzed with X-ray photoelectron spectroscopy, which shows that the surface film has the same chemical compositions and structure, as those obtained for lithium particles deposited in propylene carbonate with LiPF6. This means that HF works as a modification agent during the electrochemical deposition of lithium. The clear suppression of lithium dendrite is very important for rechargeability of lithium metal anode. In fact,... 

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