A new pigment type: Colored diblock copolymer-mica composites

L. Ghannam , H. Garay (1) , M.E.R. Shanahan (1) , Jeanne François (2) , Laurent Billon (2)

1 CMGD - Centre des Matériaux de Grande Diffusion
2 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux

New mica-polymer composite pigments have been prepared and characterized. The pigments are prepared from mica surfaces by block copolymerization of butyl acrylate (BA) and a mixture of styrene (S) and a modified alizarin (A; dye). This is performed after physical adsorption of a radical initiator with a cationic group. Some of the copolymer was desorbed from the surface and characterized by 1H NMR, size exclusion chromatography, and UV-visible spectroscopy. This desorbed copolymer fraction had a number-average molecular weight of 140 000 g·mol-1 with chemical compositions of 16% and 84% M, respectively, of poly(butyl acrylate) (PBA) and poly(styrene-alizarin) [P(S-A)]. In addition, it had a yellow coloration when in the bulk form. The remaining mica composites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. It was found that 0.07 molecules of block copolymer per nm 2 of mica remained adsorbed on the mica surface. This leads to a surprising pink color, which may be explained by the basicity of the mica surface due to the pH-color-sensitive character of the alizarin dye.

Domaines: Chimie

L. Ghannam, H. Garay, M.E.R. Shanahan, Jeanne François, Laurent Billon. A new pigment type: Colored diblock copolymer-mica composites. Chemistry of Materials, 2005, 17 (15), pp.3837-3843. ⟨10.1021/cm0478024⟩. ⟨hal-01582050⟩