Organo-Functionalized Kaolin-Group Minerals

Abstract

Abstract The kaolin-group minerals with 1:1 layered structure can be used for the synthesis of new hybrid organo-inorganic nanomaterials. An appropriate selection of the reacting molecules introduced via intercalation and/or grafting reactions and synthesis conditions may induce interesting properties, e.g. luminescence, catalytic activity, and affinity to sorb ions and molecules. To date, several new materials have been synthesized using the 1:1 layered structure as a building block. The most interesting materials could be obtained via grafting reaction involving the inner-surface OH groups of the octahedral sheet. Such materials show increased thermal stability as well as stability in aqueous solutions, unlike intercalation compounds. Note the susceptibility of the octahedral sheet of kaolinite to interact with selected organic molecules and the subsequent formation of Al–O–C bonds in the interlayer. Four different types of materials which could be obtained using kaolin-group minerals and their possible applications are discussed here: (1) kaolinite nanotubes in the synthesis of polylactide-based nanocomposites; (2) methoxy-kaolinite and intercalates with ammonium salts; (3) interlayer quaternized kaolinites and their anion-exchange properties; and (4) interlayer grafted kaolinites for heavy-metal sorption.