Complex calcium carbonate aggregates: controlled crystallization and assemblyvia an additive-modified positive-microemulsion-route

Abstract

The controlled fabrication of various kinds of complex calcium carbonate aggregates through the cooperative interactions between positive-microemulsion and soluble-additives has been systematically investigated. The polymorphs and morphologies of the products were well controlled by the existence of positive-microemulsion and the co-effect of glycine or magnesium ions. Hollow spherical aggregates of CaCO₃ consisting of monodispersed spherical nanoparticles (∼50 nm) were obtained by fine control over the thermodynamic/kinetic balance in glycin/microemulsion. Furthermore, the controlled assembly process was captured. The cooperative interactions between microemulsion and Mg²⁺ ions were first used to mimic the mineralization of CaCO₃, obtaining novel hierarchical aragonite crystals, such as novel spindle-shaped aragonite, wafer sheet-shaped aragonite and so on. The formation of these specific CaCO₃ aggregates with different crystalline phases could be ascribed to the assembly of calcium carbonate precursor (spherical or sheet-like nano-particles) with the aid of a dual template. The results imply that the specific biomimetic synthesis strategy in a dual template solution can provide a useful pathway to produce inorganic or inorganic/organic hybrid materials with a unique morphology and specific textures.