Well-defined pigments: I. Monodispersed silica-acid dyes systems

Well-defined pigment particles were produced by binding different acid dyes to monodispersed spherical silica particles. The surface of the cores was modified by coupling various aminosilanes and the dyes were converted into the acid chloride form in order to promote mutual interactions. Several methods were used to control the composition of the outermost layers of the pigments so produced. The optical properties could be altered widely, depending on the kind and amount of dye. The inter facial potential of these pigments varied with the dispersion pH and with the surface chemistry of the particles, which could be affected by the sequence of the preparation steps.