文摘
New mica-polymer composite pigments have been prepared and characterized. The pigments areprepared 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 initiatorwith a cationic group. Some of the copolymer was desorbed from the surface and characterized by 1HNMR, size exclusion chromatography, and UV-visible spectroscopy. This desorbed copolymer fractionhad a number-average molecular weight of 140 000 g·mol-1 with chemical compositions of 16% and84% M, respectively, of poly(butyl acrylate) (PBA) and poly(styrene-alizarin) [P(S-A)]. In addition, ithad a yellow coloration when in the bulk form. The remaining mica composites were characterized byFourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. It was foundthat 0.07 molecules of block copolymer per nm2 of mica remained adsorbed on the mica surface. Thisleads to a surprising pink color, which may be explained by the basicity of the mica surface due to thepH-color-sensitive character of the alizarin dye.