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Ionic Nano-Aggregates in Polyethylene-Based Ionomers: Comparison of Stem and Saxs Results

Published online by Cambridge University Press:  02 July 2020

Karen I. Winey
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut St., Philadelphia, PA19104-6272.
Jonathan H. Laurer
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut St., Philadelphia, PA19104-6272.
Brian P. Kirkmeyer
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut St., Philadelphia, PA19104-6272.
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Extract

Semicrystalline ionomers are industrially important materials in adhesives, packaging, engineering thermoplastics, coatings, and more. The most common of these are based on poly(ethylene-ran-methacrylic acid), E/MAA random copolymers partially neutralized with various cations and produced by DuPont under the tradename Surlyn®. In 1990, Register and Cooper described the morphology of semicrystalline ionomers as crystalline lamellae separated by an amorphous polymeric matrix that contains isolated cation-rich domains. Their anomalous small angle X-ray scattering experiments are consistent with the relative electron densities associated with this “three-phase” morphological model. Despite this agreement and the commercial importance of semicrystalline ionomers, a number of fundamental issues have remained unresolved regarding both the morphology of the ionic nanoaggregates and the efficiency of aggregation.

Recently, we have imaged the ionic aggregates using a scanning transmission electron microscope equipped with a field emission electron gun. This microscopy method offers the advantages of reduced phase contrast, high spatial resolution, and enhanced atomic number contrast relative to transmission electron microscopy.

Type
Advances in Polymer Characterization
Copyright
Copyright © Microscopy Society of America

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References

References:

1.Register, R. A. and Cooper, S. L., Macromolecules 1990, 23, 318.CrossRefGoogle Scholar
2.Laurer, J. H. and Winey, K. I., Macromolecules 1998, 31, 9106.CrossRefGoogle Scholar
3.Winey, K. I., et al.,Macromolecules 2000, 33, 507.CrossRefGoogle Scholar
4. This research was supported by DuPont and by the Petroleum Research Foundation.Google Scholar