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

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

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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 H-1 and C-13 NMR spectroscopy. The complexation of these SPEO's with alkali-metal ions in solution was investigated by C-13 NMR spectroscopy. The mole-fraction method was used to determine the complexation ratio of SPEO with LIClO4 at 25 degrees 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 (Delta delta) 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 delta 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. (C) 2000 John Wiley & Sons, Inc.

Item Type: Journal Article
Publication: Journal of Polymer Science Part A: Polymer Chemistry
Publisher: John Wiley and Sons
Additional Information: Copyright of this article belongs to John Wiley and Sons.
Keywords: segmented polyethylene oxides;metal-ion-polymer complex; polyethers;transetherification
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 09 Aug 2010 06:03
Last Modified: 19 Sep 2010 06:13
URI: http://eprints.iisc.ac.in/id/eprint/31166

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