Fabrication of Hierarchical CaCO₃ Mesoporous Spheres: Particle-Mediated Self-Organization Induced by Biphase Interfaces and SAMs

Highly ordered hierarchical calcium carbonate is an important phase involved in calcification by a wide variety of invertebrate organisms, and its formation is of technological interest in the development of functional materials. In this article, porous CaCO(3) hierarchical microspheres with a hedgehoglike appearance have been fabricated on the flexible substrate under mild conditions. There are two points that play important roles in the regular organization of the terminal products: one is the biphase interfaces, which are generated by organic solvent n-hexane and an aqueous saturated solution of Ca(OH)(2), and the other is hydroxyl-terminated monolayers assembled on the flexible PET (poly(ethylene terephthalate)) substrate. The SEM images show that novel CaCO(3) hierarchical microspheres consist of densely stacked "shuttles" by the oriented self-organization of CaCO(3) nanoparticles. The IR and XRD spectra indicate that the as-synthesized products are composed of a calcite phase obtained by an ACC (amorphous calcium carbonate)-to-calcite transformation. In view of the results, a nanoparticle-mediated self-organization process induced by biphase interfaces and SAMs template is proposed for the integration of functional materials and nanodevices.