Borate polymers

Figure 7 Temperature dependence of ionic conductivity for lithium borate polymer electrolytes prepared via polymer reactions.

Table 4 Ionic Conductivity of Lithium Borate Polymers Prepared via Polymer Reactions...

To avoid problems associated with these polymer reactions, the direct synthesis of lithium borate polymer electrolytes37 was undertaken by dehydrocoupling polymerization using lithium mesitylhydroborate40 (scheme 7). 

Lithium mesitylhydroborate was prepared by reaction of mesitylmagnesium bromide with trimethoxyborane and subsequent reduction with LiAlH4. The polymerization was performed by adding a THF solution containing a slight excess of lithium mesitylhydroborate to oligo(ethylene oxide) in THF. After treatment with alcohol, the lithium borate polymers were obtained as transparent soft solids soluble in methanol, THF, and chloroform. 

Before treatment with alcohol, the ionic conductivity of lithium borate polymers was 6.23 X 10-5 to 2.07 X 10-7 Scm-1 at 50°C. The maximum ionic conductivity was observed for the polymer with a PE040o spacer unit. After the polymer reaction with alcohols, glass-transition temperatures of these polymers were found to be -52 to 39°C, which was higher than that of poly(lithium mesitylhydroborate) ( 69°C). 

The ionic conductivity of this lithium borate polymer bearing the methoxybo-rate unit (9a) was 8.77 X 10 6Scm 1 at 50°C (Fig. 8). This value was lower than that observed before the polymer reacted with methanol. However, it was still greater... 

Boron and arsenic are natural components of soil and are both present as oxyanions. Boron is present as boric acid or borate polymers, and arsenic is present as arsenate. While boron is weakly held by soil, arsenic is similar to phosphate in its interactions with soil constituents. Boron is an essential nutrient for plants however, it is also toxic to plants at relatively low levels. Arsenic is toxic. The laboratory chemistry of both of these elements is well understood, but their environmental chemistry, speciation and movement, is less well understood [23-27],... 

These examples illustrate not only how cations direct the structures of isolated borate anions and the spatial arrangements of extended borate polymers, but also how they determine chemical and physical properties of... 

Fontaine, G., Bourbigot, S., and Duquesne, S. 2008. Neutralized flame retardant phosphorus agent Facile synthesis, reaction to fire in PP and synergy with zinc borate. Polym. Deg. Stab. 93 68-76. 

The borate-HPG cross-links are labile and lead to the gels healing rapidly after shear. A number of studies 16, 19, 20) have used NMR to investigate boron-hydroxyl interactions. NMR measurements 16) on model galactopyranose and mannopyrannose sugars showed that the lifetime of a borate-polymer interaction is on the order of 1 ms. Some evidence indicates that the borate-polymer interaction occurs through cis hydroxyls on the sugar residues (79), which is the reason that other polysaccharides with equal numbers of hydroxyls but without cis hydroxyls cannot be cross-linked. 

Xu, W. Sun, X. G. Angell, C. A., Anion-trapping and polyanion electrolytes based on acid-in-chain borate polymers, Electrochim. Acta 2003,48, 2255-2266. 

Borate polymer growth (Rg radius of gyration) versus aging time in 100% RH water vapor for 0.3 LiOMe-0,7 B(OBu")3 sols prepared with initial H2O OR ratios of 0.4 or 0.3. Gel point for the 0.4 sampie indicated. From Drinker et at. 1185]. 

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