High Ionic Strength Promotes the Formation of Spherical Copolymer Particles

Authors

  • Nancy Weber,

    1. Max Planck Institute of Colloids and Interfaces, Department of Colloid Chemistry, Am Mühlenberg 1, D-14476 Golm, Germany
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  • Miriam M. Unterlass,

    1. Max Planck Institute of Colloids and Interfaces, Department of Colloid Chemistry, Am Mühlenberg 1, D-14476 Golm, Germany
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  • Klaus Tauer

    Corresponding author
    1. Max Planck Institute of Colloids and Interfaces, Department of Colloid Chemistry, Am Mühlenberg 1, D-14476 Golm, Germany
    • Max Planck Institute of Colloids and Interfaces, Department of Colloid Chemistry, Am Mühlenberg 1, D-14476 Golm, Germany
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Abstract

A comprehensive experimental study of thermally initiated styrene-styrene sulfonate emulsion copolymerization in the presence of 15 different low-molecular-weight electrolytes clarifies the enormous influence of both the concentration and nature of the added salt on the outcome of the polymerization. The ionic strength (IS) has a direct influence on the styrene sulfonate content in the final copolymer and determines whether the physical state of the final reaction product is a solution or dispersion. Stable latexes have been obtained for IS as high as 18 M. Electron microscopy images show irregularly shaped clusters at low and spherical particles at high IS. The properties of the copolymer molecules and dispersion can be additionally modified by the chemical properties of the counter- and coions introduced with the salt.

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