| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 195818 | Electrochimica Acta | 2007 | 8 Pages |
DSC indicates that first-heating endotherms at 95 and 100–115 °C in poly(tetramethylene oxide)-based polymers with LiClO4 and LiBF4, respectively, arise from the decomposition of phase-separated LiClO4·3H2O and a pre-melting transition in phase-separated LiBF4 and not from organized adducts with poly(tetramethylene oxide) as asserted by Akbulut et al. and other literature. Water in the LiClO4 system, at least (absent in freeze-dried samples), could account for higher conductivities reported by Akbulut et al. than observed by the present authors. Irreversibility of log σ versus1/T in these weakly ionophilic systems apparently arises from slow dissolution of lithium salts together with morphological changes in mixtures of the self-organising systems CmOn (I) with the ‘grain boundary bridging’ copolymer –[–(CH2)4–O–]x–(CH2)12– (II). A three-component system I:II:LiBF4 to which 9 wt% of tetrahydrofuran had been purposefully added showed deterioration in conductivity compared with the system without THF addition. This suggests that solvent-inhibition of self-organization is contrary to the suggestion by Akbulut et al. that irreversible transformation to a high ambient conductivity (σ = 10−4 to 10−3 S cm−1) regime arises from plasticization by the 3 wt% of volatiles, generated by thermal decomposition of II in a three-component mixture, that they report. The irreversible transformation to higher conductivities is also observed in systems heated to maximum temperatures between 50 and 80 °C for which degradation was shown to be negligible.
