Summary
The reaction between carboxylic acids in benzene solution and suspended zinc oxide particles was investigated by means of infrared spectrometry. The results show how the carboxyl groups react with the zinc oxide forming zinc carboxylate groups at the chemisorption. The chemisorbed acid forms a multilayer at the surface, which gives a new explanation of the protective action of adsorbed acids against flocculation of the particles in nonpolar solvents. The temperature-dependence of the spectra showed transitions at the same temperatures and of the same kind as the corresponding zinc carboxylates, whose spectra were also recorded. The zinc soaps exhibited thermotropic behaviour, and lyotrophy is suggested as the explanation of the multilayer formation.
Zusammenfassung
Mit Hilfe der Infrarotspektrometrie wurde die Einwirkung von Stearinsäure und ölsäure auf Zinkoxid untersucht, das in Benzol suspendiert worden war. Durch Carboxylatbildung wird eine multimolekulare Schicht der Säuren auf der Oberfläche der Zinkpartikel ausgebildet. Die Partikel werden dadurch von der Flokkulation in nichtpolaren Lösungsmitteln geschützt. Die Temperaturabhängigkeit der Spektren entspricht der der Zinkcarboxylate.
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Roberts, K., Friberg, S. Phase transitions of adsorbed carboxylic acids on zinc oxide and of zinc soaps. Infrared and X-ray diffraction investigations. Kolloid-Z.u.Z.Polymere 230, 357–362 (1969). https://doi.org/10.1007/BF01520610
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DOI: https://doi.org/10.1007/BF01520610