Biomimetic Synthesis of Calcium Carbonate Polymorphs Using the Lamellar Lyotropic Liquid Crystalline Systems of Calcium Dodecyl Sulfate.

Lyotropic liquid crystalline phases have immediate relevance in biology because of the prevalence of organized lipid structures in living systems. The incorporation of hydrophilic reagents in water domains with well-defined nanoscale geometry favors the construction of nanostructured materials of inorganics, and/or the inorganic−organic hybrids. In this paper, the lamellar mesophases composed of calcium dodecyl sulfate (CDS), n-pentanol, and ammonia (5 wt% NH 3·H 2O in water) were constructed and used as the precipitation media of calcium carbonate (CaCO 3). Under the atmosphere of carbon dioxide gas, the occurring solid−liquid−gas reaction resulted only in rhombohedral calcite particles at the beginning, then ultimately in layer-cake aggregates of calcite and stick-bundle aggregates of aragonite. Furthermore, the aragonite content increased with the proceeding time interval of the three-phase reaction, indicating a special crystallization habit of CaCO 3in the lamellar mesophases of CDS. Aside from these, the influence of the structure of CDS lamellar mesophases on the formation of CaCO 3crystals is also discussed. These imply an effective biomimetic approach for the simultaneous fabrication of metastable aragonite and thermodynamically stable calcite under mild conditions. [ABSTRACT FROM AUTHOR]