Solution cation-binding properties of segmented polyethylene oxide- a 13C NMR spectroscopic study

Jayakannan, M. ; Ramakrishnan, S. (2000) Solution cation-binding properties of segmented polyethylene oxide- a 13C NMR spectroscopic study Journal of Polymer Science Part A: Polymer Chemistry, 38 (15). pp. 2635-2644. ISSN 0887-624X

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Two segmented polyethylene oxides, SPEO-3 and SPEO-4, were prepared using a novel transetherification methodology. Their structures were confirmed by 1H and 13C NMR spectroscopy. The complexation of these SPEO's with alkali-metal ions in solution was investigated by 13C NMR spectroscopy. The mole-fraction method was used to determine the complexation ratio of SPEO with LiClO4 at 25 °C, which showed that these formed 1:1 (polymer repeat unit/salt) complexes. The association constant, K, for the complex formation was calculated from the variation of the chemical shift values with salt concentration, using a standard nonlinear least-square fitting procedure. The maximum change in chemical shift (Δδ) and the K values suggest that both SPEO-3 and SPEO-4 formed stronger complexes with lithium salts than with sodium salts. Unexpectedly, the K values were found to be different, when the variation of δ of different carbons was used in the fitting procedure. This suggests that several possible complexed species may be in equilibrium with the uncomplexed one. Structurally similar model compounds were also prepared and their complexation studies indicated that all of them also formed 1:1 complexes with Li salts. Interestingly, it was observed that the polymers gave higher K values suggesting the formation of more stable complexes in polymers when compared to the model analogues.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
Keywords:Segmented Polyethylene Oxides; Metal-ion-polymer Complex; Polyethers; Transetherification
ID Code:67243
Deposited On:29 Oct 2011 12:03
Last Modified:29 Oct 2011 12:03

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