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1094976 
Journal Article 
Effect of Molecular Weight and Salt Concentration on Conductivity of Block Copolymer Electrolytes 
Panday, A; Mullin, S; Gomez, ED; Wanakule, N; Chen, VL; Hexemer, A; Pople, J; Balsara, NP 
2009 
1 
Macromolecules
ISSN: 0024-9297
EISSN: 1520-5835 
42 
13 
4632-4637 
English 
WOS:000268138500044 
The ionic conductivity, sigma, of mixtures of nearly symmetric polystyrene-block-poly(ethylene oxide) copolymers and Li[N(SO(2)CF(3))(2)] (LiTFSI) salt was measured as it function of molecular weight, salt concentration, and temperature. The molecular weight of the poly(ethylene oxide) block, M(PEO), was varied from 7 to 98 kg/mol. The molar ratio of lithium to ethylene oxide, r, was varied from 0.02 to 0.10. In general, sigma increases with increasing M(PEO) for all values of r. The data can be summarized by plots of normalized conductivity, sigma(n), versus M(PEO). where sigma(n) = sigma/(f phi(PEO)sigma(PEO)), phi(PEO) is the PEO volume Fraction in the copolymer, sigma(PEO) is the conductivity of PEO homopolymer, and f is a morphology-dependent factor set equal to 2/3 for our lamellar samples. The temperature-dependent conductivity data at a given salt concentration collapse onto a single curve when plotted in this formal. At r = 0.085 sigma(n) values reach a plateau in the vicinity of it unity in the high M(PEO) limit. At other values of r, sigma(n) continues to increase with M(PEO) within the experimental range and reaches a value of around 0.5 in the high M(PEO) limit.