Lithium Phosphate Polymerization

The step-growth polymerization of dibasic lithium phosphate is discussed next as an example of a polymerization reaction followed by immediate crystalhzation to the polymer, studied largely by thermal analysis [14,15]. It illustrates that not only organic molecules can be flexible macromolecules, but also inorganic ones. The two major techniques used for the analysis are differential scanning calorimetry (DSC, see Sect. 4.3) and thermogravimetry (TGA, see Sect. 4.6). The reaction equation is  

The reaction product, the polymeric phosphate (formerly called metaphosphate) has a high melt viscosity, as expected for a polymer. The step-reaction polymerization becomes clearer when following the fate of the dihydrogen phosphate ion  

The DSC heating-trace in Fig. 3.16 shows several comphcations during the nonisothermal reaction. First, there is the melting endotherm of the LiH2P04 monomer, beginning at about 470 K (AT in the endothermic direction is proportional to the consumed heat to raise temperature). In addition to the fusion, other endothermic effects are due to the evaporation of water evolved in the chemical reaction. The TGA trace of Fig. 3.17 registers the changes in mass, and records quantitatively the 

As is typical for step-growth polymerizations, each molecule in the reaction mixture has two reactive -OH groups, and for each H2O molecule lost, one bond is formed. Furthermore, [H ] is also proportional to [-OH] if no external acid is added. In Fig. 3.19 a kinetics is assumed, similar to the just discussed third-order esterification (n = 3). This assumption is next shown to fit the measured data. Writing for the concentration [POH] = [POH]o(l - p), where [POHl is the initial concentration (= 2Mo) and p the fractional progress of the polymerizarion, one can see that the rate of polymerization dp/dt = k[POH](, (l - p)l The connection to the boxed equation is given by k = k[POH]/. Also, written is the temperature-dependence of k as described in Fig. A.7.2. 

Since the TGA-trace in Fig. 3.18 indicates that the fast reaction is complete at p = 0.5, one expects that the rate constant k for the formation of a dimer is larger than k, for further polymerization as suggested in the summary at the bottom of Fig. 3.14. Assuming that only the monomer-to-dimer rate is faster than the rest of the polymerization, a full set of kinetic equations as indicated in Fig. 3.20 can be solved. The monomer concenttation decreases due to the formation of dimers (with a rate constant k,) and all other species that react need the rate constant k,. Analogously other 

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Chromium(m) in lithium phosphate glass appears to be octahedrally co-ordinated and the value of peff (3.2 BM) suggests that some exchange interaction between the metal centres occurs in this medium.147 Polymeric complexes of chromium(m)... 

Three detailed applications of thermogravimetry are described with more quantitative interpretations, i.e., efforts are made to develop information on the kinetics and equilibrium. The calcium oxalate/carbonate decomposition is treated first. The lithium hydrogen phosphate polymerization has been discussed above as a step-reaction in Sect. 3.1 (Figs. 3.16-22). Finally, the method and some examples of lifetime determinations based on TGA are shown at the end of this section. 

Clinical chemistry, particularly the determination of the biologically relevant electrolytes in physiological fluids, remains the key area of ISEs application [15], as billions of routine measurements with ISEs are performed each year all over the world [16], The concentration ranges for the most important physiological ions detectable in blood fluids with polymeric ISEs are shown in Table 4.1. Sensors for pH and for ionized calcium, potassium and sodium are approved by the International Federation of Clinical Chemistry (IFCC) and implemented into commercially available clinical analyzers [17], Moreover, magnesium, lithium, and chloride ions are also widely detected by corresponding ISEs in blood liquids, urine, hemodialysis solutions, and elsewhere. Sensors for the determination of physiologically relevant polyions (heparin and protamine), dissolved carbon dioxide, phosphates, and other blood analytes, intensively studied over the years, are on their way to replace less reliable and/or awkward analytical procedures for blood analysis (see below). 

The alkylation procedure is salt dependent and is retarded by lithium salts. In the absence of the latter, the reaction between BuLi and triethyl phosphate in thf is 85% complete after 0.5 h at 40 °C whereas, in the presence of LiBr, only 5% of the phosphate ester is consumed under similar conditions the effect is particularly marked in the use of MeLi, when lower reactivity is probably a consequence of the polymeric nature of the reagent In the absence of lithium salts, even the more highly hindered tributyl and... 

Benkhoucha R, Wunderlich B (1978) Crystallization During Polymerization of Lithium Dihydrogen Phosphate. Part I. Nucleation of the Macromolecular Crystal from the... 

Section 2.4 reviews organophosphorous compounds as nonflammable or flame-retardant electrolytes for lithium-ion batteries. These include organic phosphates, phosphites, phosphonates, or phosphazenes, and a phosphonamidate as co-solvents or additives. The author introduces polymeric gel electrolytes containing these flame-retardant components. 

Synonims 1,2-cyclohexanedicarboxylic, acid calcium salt octacosanoic acid, calcium salt (2 1) calcium difluoride propanedioic acid, calcium salt (1 1) 1,5-pentane dicarboxylic acid, calcium salt (lR,2R,3S,4S)-rel-bicyclo[2.2.1]heptane-2,3-dicarboxylic acid, disodium salt mixture of polycarbonic acid salt and inorganic carbonate in a polymeric carrier, sodium 2,2 -methylene-bis-(4,6-di-tert-butylphenyl)phosphate bicyclic (2,2,1) heptane di-carboxylate 1,2-cyclohexanedicarboxylic acid, calcium salt -i- zinc stearate bicyclo[2.2.1]heptane-2,3-dicarbo lic acid, disodium salt, (IR, 2R, 3S, 4S)-rel-and a blend of amorphous silicon dioxide coated wilh 13-docosenamide in a 1 1 ratio proprietary zinc compound octacosanoic acid, calcium salt (2 1) benzoic acid, lithium salt zinc monoglycerolate sodium benzoate encapsulated sodium salts of carbonic and poly-carboxylic acids with styrene and SEES rubber carrier resins zinc,[l,2,3-propanetriolato(2-)-k01,k02]homopolymer, stereoisomer... 

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