Unique crystal morphology of hydrophobic CaCO3 composite by sodium trisilanolate in a mixture of a water-miscible organic solvent and water

We describe unique crystal morphologies of hydrophobic CaCO3 crystals in a mixture of water and tetrahydrofuran (THF). After addition of sodium trisilanolate [(c–C5H9)7Si7O9(ONa)3] <f>(1¯)</f> into the mixture of water and THF, calcium reactants (0.1 M CaCl2 and 0.1 M (NH4)2CO3) were added to the reaction mixture at 30°C. FT-IR and SEM images showed that concave terraced calcite was obtained in 80% THF solution. In the absence of <f>1¯</f>, the crystalline product was a mixture of rhombohedral calcite with aggregated vaterite particles. The hydrophobic modified surface of the concave terraced calcite was confirmed by the contact angle and dispersability in organic solvents. [Copyright &y& Elsevier]