Studies on the colloidization and stability of layered M(IV) phosphates in aqueous amine solutions

For the purpose of preparing pillared materials and multifunctional films, the colloidization and hydrolysis of alpha-Zr(HPO4)(2) . H2O (alpha-ZrP), alpha-Sn(HPO4)(2) . H2O (alpha-SnP) and alpha-Ti(HPO4)(2) . H2O (alpha-TiP) in alkylamine and alcohol amine solutions were investigated. The phosphates colloidize at a low level of amine intercalation but recrystallize at high levels of amine uptake. Alcohol amines are more efficient in colloidization of phosphates than alkylamines, and in the same amine solution alpha-ZrP and alpha-SnP colloidize more readily than alpha-TiP. The hydrolytic reaction of the phosphates following the course of intercalation in different amine solutions were studied. The dissolution of the metal ions accompanying the hydrolysis of HPO42- leads to the destruction of the sheet structure. The strong hydrolytic reaction of alpha-TiP causes it to colloidize with difficulty. The phase transformations of the wet amine intercalates during air drying were detected by XRD. The interlayer amine molecules may arrange in monolayer, bilayer or intermediate orientation, depending on the nature and content of the amines.