Polymorph Control Of Calcium Carbonate And The Synthesis And Transformation Of ACC

Recently, material synthesis that simulates biomineralization in organic systems such as calcium carbonate, magnetic iron oxide, and amorphous silica of exquisite morphology, has attracted increasing interest because of their structural and functional value. CaCO3is one of the standard model systems for studying biomineralization because of its abundance in nature and important industrial application. Interestingly, polymorph selection of CaCO3mineral is a key step for studying biomineralization process of CaCO3mineral. Therefore, polymorph control of CaCO3has been a hot research field. The mail results can be summarized as follows:1. We have demonstrated for the first time a facile double-jet method for polymorph discrimination of CaCO3in aqueous solution under mild conditions without using any organic additives. It has been demonstrated that the thermodynamic and kinetic regimes, which contribute to the polymorph control, can be manipulated in solution by simply tuning the temperature of the reaction system. The present study may further provide clues for a deeper understanding of the biomineralization process of CaCO3as it occurs in nature. Furthermore, this template-free polymorph discrimination method in aqueous solution system may shed new light on the controlled crystallization of other inorganic materials.2. The role of the temperature sensitive polymers in mineralization of calcium carbonate at different temperature using the so-called double-jet method has been reported. Employing the poly (ethylene glycol)-poly (N-isopropyl acrylamid)-poly (acrylamido methyl propane sulfonate)(PEG-PNIPAM-PAMPS), the unusual homogeneous aragonite flowers with controlled surface structures can be prepared at50℃. Herein, a new mineralization of CaCO3mechanism about PNIPAM is firstly introduced due to the interesting property of the temperature-sensitive triblock copolymer. In addition, three anhydrous crystalline phases, i.e. calcite, aragonite and vaterite, can be nicely captured simply by this choice of the reaction temperature in the present system. Furthermore, this new mineralization of calcium carbonate mechanism about PNIPAM may provide a new route for the controlled crystallization of other inorganic materials.3. The gram-scale, low cost, rapid synthesis of highly stable Mg-ACC nanoparticles has been systhesized. The possible structure of Mg-ACC can be defined as Mg0.15Ca0.85CO3H2O0.85.The molar ratio of Mg2+:Ca2+:CO32-and the concentration (CaCl2, Na2CO3, and MgCl2) play important role in the Mg/Ca molar ratio of the obtained Mg-ACC. As-prepared Mg-ACC nanoparticles can be preserved for over one year without crystallization by storing either its dry powder at-5℃or storing it in ethanol at5℃. The successful access of Mg-ACC nanoparticles in large scale would be useful for further biomineralization study and industry applications.4. Finally, a facile confined crystallization method has been developed to incorporate high content Mg in calcite by crystallization of compact tablet of Mg-ACC in water without using any organic additives. It has been demonstrated that the confined crystallization plays a key role in preventing the escape of Mg2+and incorporation of magnesium in the calcite lattice, which may suggest that similar roles of confined environment in the formation of biological magnesian calcite. In addition, some intermediate states can be captured in this special confined crystallization process of the compact tablet of magnesian amorphous calcium carbonate nanoparticles.