Transformation of novel morphologies and polymorphs of CaCO3 crystals induced by the anionic surfactant SDS

Anionic surfactant, sodium dodecyl sulfate (SDS), was used as a template to modify the formation of CaCO3 crystals. Aragonite was produced when the concentration of SDS was controlled at 0.5 mM. The rod-shaped aragonite aggregated by block-like particles was fabricated. Pure vaterite with a novel flower-shaped morphology was obtained when the concentration of SDS was 1.0 mM. When the concentration of SDS was increased to 2.5 mM, a mixture composed of vaterite and calcite was produced. And the as-prepared sample showed various morphologies, including tube-shaped, rod-shaped and hexagonal structures. However, the most interesting result is that rhombohedral calcite may be transformed from hexagonal vaterite. This result may prove useful to the further investigation of the processes of biomineralization. (C) 2010 Elsevier B.V. All rights reserved.