Ionic interactions and transport properties in methyl terminated poly(propylene glycol)(4000) complexed with LiCF{sub 3}SO{sub 3}
- Umea Univ. (Sweden)
Alternating current (ac) impedance, restricted diffusion, and vibrational spectroscopic (Raman and IR) measurements have been conducted on complexes of methyl capped poly(propylene glycol) of molecular weight 4000 and LiCF{sub 3}SO{sub 3} salt. The relative concentrations of anions in different chemical environments have been calculated from an analysis of the symmetric anion SO{sub 3} stretch (Raman) over a wide concentration range. Comparisons are made to previous studies on hydroxyl capped PPG systems, and we find that polar polymer end groups play an important role in the solvation of the salt. The relative fraction of anions interacting directly with lithium cations is considerably higher over the entire concentration range in the present study, and we infer the existence of negatively charged ionic aggregates in the solutions. We also note that the fraction of spectroscopically `free` anions increases with increasing salt concentration in the ether oxygen to alkali metal cation ratio (O:M) range 502:1 to 12:1, contrary to a decrease reported for the analogue hydroxyl terminated electrolytes. The ionic conductivity has a more pronounced concentration dependency in the methyl capped system; notably, the molar conductivity ({Lambda}) increases dramatically with increasing salt concentration passing through a relatively sharp maximum at O:M = 20:1 at room temperature. 71 refs., 8 figs., 1 tab.
- OSTI ID:
- 501913
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical Journal Issue: 2 Vol. 101; ISSN 1089-5647; ISSN JPCBFK
- Country of Publication:
- United States
- Language:
- English
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