Polymer electrolytes phosphazene

Polymer Electrolytes Based on Poly[bis(methoxyethoxyethoxy)phosphazene] 203... 

The first polyorganophosphazene to be studied as polymer electrolyte was poly-[bis(methoxyethoxyethoxy)phosphazene] (MEEP), V, synthesized by Allcock [272] in 1984. 

In conclusion, polymer electrolytes based on phosphazene backbone and containing ether side chains are, after complexation with alkali metal salts, among the highest ionically solvent-free polymer salt complexes, with conductivities in the order of 10" -10" S cm However, these conductivities are still below the value of 10 S cm" which is considered to be the minimum for practical applications. Therefore the design of new polyphosphazenes electrolytes with a higher conductivity and also a higher dimensional stability still remains a challenge for future researchers. 

Numerous amorphous room temperature polymer electrolytes are also known. A variant of PEO which interspaces methylene moieties with ethylene moieties is also amorphous at room temperature. Its repeat structure is (—O—CH2—O—C2H4—). Another intensively studied Li-ion conductive amorphous polymer is known as MEEP. This acronym stands for methoxy-ethoxy-ethoxy-phosphazene. The polymer structure is a repeating (—N=PR2—) phosphazene unit with two alkoxy chains dangling from the phosphorous atoms, i.e., (—N=P—(O—C2H4 —O—C2H4—O—CH3)2—). 

In order to appreciate the utility of appropriately substituted poly(phosphazenes) as hosts in polymer electrolytes it is essential to obtain a preliminary idea about the nature of bonding in these polymers [179,181,185,186]. 

The backbone conformational flexibility of poly(phosphazenes) is important for ionic mobility and hence suitably substituted poly(phosphazenes) have attracted considerable interest as hosts in polymer electrolytes. 

Table 11. Conductivity values of polymer electrolytes derived from surfactant substituted poly (phosphazenes) PP(I) and PP(II)...

Howevei although general tendencies can be observed, it would appear that hydrophilicity alone cannot explain hydrolytic sensitisation for all polyphosphazenes. For example, oligoethyleneoxy side chains, including poly[ /s(2-(2-methoxyethoxy)ethoxy)phosphazene], and its many structural variations [33], used as solid polymer electrolytes, are reported to be biostable, whereas structurally similar polymers with P-NH-R attachments, instead of the P-O-R are known to undergo hydrolytic degradation [34]. Also, ethyl esters of serine and... 

This electrolyte displays high room temperature conductivity which in most cases is 2-3 orders of magnitude greater than similar PEG complexes. The success of the phosphazene-based electrolyte led us to consider other polymer electrolytes with inorganic backbones. 

Conner, D. A., Welna, D. T., Chang, Y., AUcock, H. R., Influence of terminal phenyl groups on the side chains of phosphazene polymers Structure-property relationships and polymer electrolyte behavior, Macromolecules, 2007, 40, 322-328. 

Chen-Yang, Y. W., Hwang, J. J., Chang, F. H., Polyphosphazene electrolytes. 1. Preparation and conductivities of new polymer electrolytes based on poly[i>w(amino) phosphazene] and lithium perchlorate, Macromolecules, 1997, 30, 3825-3831. 

AUcock, H. R., Prange, R., Hartle, T. J., Poly(phosphazene-ethylene oxide) di-and triblock copolymers as sohd polymer electrolytes, Macromolecules, 2001, 34, 5463-5470. 

Adamic, K. J., Greenbaum, S. G., Abraham, K. M., Alamgir, M., WintersgiU, M. C., Fontanella, J. J., Lithium-7 nmr study of polymer electrolytes based on composites of poly[i>w((methoxyethoxy)ethoxy)phosphazene] and poly(ethylene oxide). Chemistry of Materials, 1991, 3, 534-538. 

Chen-Yang, Y. W., Chen, H. C., Lin, F. J., Liao, C. W., Chen, T. L., Preparation and conductivity of the composite polymer electrolytes based on poly[fcw(methoxyethoxyethoxy) phosphazene], LiC104 and a-Al203, Solid State Ionics, 2003, 156, 383-392. 

For solid polymer electrolytes, the goal is to create highly conductive materials that function in the absence of water. Triazole and aminotriazole have been attached to linear phosphazenes to gain conductivity. A sequential synthesis was performed where half of the chlorines from... 

In general, polymer electrolytes are mixture of salts with soft polar polymers such as PEG and poly(methoxyethoxyethoxy)phosphazene (MEEP) and have been intensively studied since their discovery. The mobility of ions in typical polymer electrolytes is well known to be intimately coupled to the segmental motion of the host polymer matrix. To increase the segmental motion and thereby conductivity of polymer electrolytes, a variety... 

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