Interaction of organic molecules with powder surfaces

Fig. 1: Nature and number of functional groups

Fig. 2: Effect of the position of functional groups on the adsorption behavior

Contact: André Studart

The interface between organic molecules and inorganic powders is known to govern several properties of composite materials and colloidal suspensions used in a wide number of applications in food, cosmetics, ceramic, polymer and paint industries.
We study the interaction of organic molecules with inorganic powder surfaces in order to tailor optimum surfactants and coupling-agents for ceramic colloidal suspensions. On ceramic powder surfaces, small organic molecules of less than 500 g/mol show significant specific adsorption only if they have adsorbing functional groups. These functional units like carboxyl, hydroxyl or amino groups may substitute for surface hydroxyl groups and are able to form complexes between the metal ion of the surface and the specific adsorbing molecule. A series of molecules based on a benzene ring substituted with (-OH) and (-COOH) groups has been used to derive guidelines for the selection of dispersants for a given colloidal forming process. The relation between the molecular structures of low-molecular-weight organic dispersants and their influence on the properties of alpha-Al₂O₃ suspensions has been addressed. In particular, the effect of the nature, number and position of the functional groups attached to the benzene ring on the adsorption behaviour of these molecules on alpha-Al₂O₃ and on the electrophoretic mobility of alumina particles in aqueous suspension has also been examined.

For more information, consult the papers by Hidber, Graule, Studart, Tervoort and Rezwan in our literature database.