Spherical silica particles coated with lamellar nanocomposites based on a hydrophobic functionalized phyllosilicate

The surface of spherical silica particles (monodisperse, 2.6 & mu;m) was modified with inorganic-organic lamellar ordered hybrids for applications as hydrophobic dye supports in cosmetics. The inorganic-organic multilayers comprised a 2:1 phyllosilicate (two sheets of linked SiO4 tetrahedra with one sheet of M2-3(OH)6 octahedra, where M is either magnesium or aluminum), consisting of octyl chains directly bonded to the inorganic sheets via Si-C covalent bonds. Octyltriethoxysilane was allowed to react at room temperature with spherical silica and aluminum acetylacetonate in a mixed aqueous solution of NaOH and NaCl at pH 10. The formation of a 2:1 phyllosilicate grafted with an octyl chain was confirmed by X-Ray powder diffraction, where a lamellar structure with the d001 value of 2.4 nm was displayed. The lamellar structure included the isomorphic substitution of Si by Al and the formation of C-Si-O-Aloct bonds, as shown in 29Si-and 27Al-magic angle spinning (MAS)-nuclear magnetic resonance (NMR) spectra. Further, the 23Na-MAS NMR spectrum indicated the incorporation of Na aquo complex cations into the organophyllosilicate. The hydrated Na ions were exchanged with a cationic dye (methylene blue) to be adsorbed. An anionic dye (Phloxine B), which has frequently been used as cosmetic pigments, was adsorbed onto the resulting hybrid particles when Al3+ was present in the dye solution. The hydrophobic dye supports can be used instead of plastic beads to reduce marine pollution.