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High Ionic Strength Promotes the Formation of Spherical Copolymer Particles
Author(s) -
Weber Nancy,
Unterlass Miriam M.,
Tauer Klaus
Publication year - 2011
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201100206
Subject(s) - copolymer , styrene , sulfonate , ionic strength , polymer chemistry , dispersion (optics) , salt (chemistry) , ionic bonding , chemical engineering , materials science , emulsion polymerization , polymerization , dispersion polymerization , chemistry , aqueous solution , polymer , composite material , sodium , ion , organic chemistry , physics , optics , engineering
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.