Effects of the solid surface and polyelectrolyte on the two-dimensional organisation of calcium carbonate particles

Abstract

Calcium carbonate (CaCO₃) particles were precipitated from supersaturated solutions. The effects of the poly(sodium 4-styrene sulfonate) used as an additive and of the silicon wafer surface present in the precipitation medium on the two-dimensional organisation of CaCO₃ particles were investigated. The nature of the solid substrate was varied, using a hydrophilic nonmodified silicon oxide containing hydroxylated surface groups, and a hydrophobic silicon oxide modified with n-hexadecyltrichlorosilane. The micrographs indicate that the surface ordering and densities of the CaCO₃ particles depend on the nature of the silicon wafer dipped during the precipitation experiments. Two-dimensional ordering of single and aggregated CaCO₃ particles were obtained, respectively, on the homogenous hydrophobic n-hexadecyltrichlorosilane and on the hydrophilic nonmodified silicon oxide surfaces. The results indicate that the surface coating can be controlled not only by the nature of the solid substrate and additives present in the precipitation medium but also by the coating mode.