The local environment of the neutralizing cation was examined by extended X-ray absorption fine structure spectroscopy in a series of model polyurethane ionomers. Polyol type, polyol molecular weight and pendant anion type had small effects on cation local environment. Sample preparation conditions had a noticeable effect in one case. The type of cation was the dominant factor in determining local ordering. The degree of local order decreased with cation type in the order Ni 2+ > Sr 2+ > Cd 2+, in agreement with the trend of decreasing tensile properties with cation type. Hydration of Ni 2+-neutralized ionomers induced no change in the Ni 2 + local environment for a sulphonated ionomer, but hydration caused a rapid change in the local structure of the analogous carboxylated ionomer. The changes were in accord with water molecules coordinating to the Ni z+ cation.
Посилання на статтю:
Extended X-ray absorption fine structure spectroscopic analysis of cation local environment in model polyurethane ionomers / Susan A. Visser and Stuart L. Cooper* // Polymer. – 1992. – Vol 33. – P. 930-937.