Solution-Based Synthesis, Growth Mechanism And Property Of Several Minerals

In this dissertation, versatile methods were used to control size, shape, polymorph and hierarchy of CaCO3, CeOHCO3 and rutile-TiO2 minerals. For biomineralization study, one double hydrophilic block copolymer with a rigid functional group (PEG-b-hexacyclen macrocycle) directed round disc-like calcite crystals with layered structure, which is similar to nacre of Haliotis rufescens. Amorphous calcium carbonate (ACC) nanoparticles were synthesized by a gas-diffusion process, which was used as precursor for transformation and crystallization of CaCO3 polymorph. It is found that a fine adjustment of thermodynamic-kinetic equilibrium has a strong effect on the formation of metastable kinetic phase. M@TiO2 (M=Ag, Au, Pt) naonocomposites can be successfully synthesized by a photoreduction process. Ag@TiO2 and Au@TiO2 exhibited excellent antibacterial properties against E. coli., when the dosage of metal concentration reached to 10 g/ml. When these nanocomposites fulfilled a photooxidation polymerization process, metal@TiO2-conductive poly(phenylenediamine) hybrid materials formed. The main results can be summarized as following:1. PEG-b-hexacyclen macrocycle was used as crystal growth modifier, controlling formation of layered structure CaCO3 with similar structure of nacre. Besides the epitaxial match between pattern of functional group of the copolymer and special crystal face of calcite, particle stabilization, crystallization time, time for polymer rearrangement, and surface-ion density play roles on the formation of this layered structure.2. In a gas-diffusion process, well-dispersed amorphous calcium carbonate nanoparticles were synthesized in ethanol. The nanoparticles can be stable in ethanol for several months, and its size distribution doesn't change even after condensation or ultracentrifugation. Crystallization behaviour of the amorphous calcium carbonate were investigated, a lot of structures, such as calcite rhomb, curved CaCO3 nanofibre, vaterite nanofibre, and calcite dendritic crystal, can be formed when the water content and pH in the water-ethanol mixed solvents changed.3. Adjusting the water/ethanol ratio, a complete polymorph evolution from thermodynamic stable phase to metastable phase happened in the case of CaCO3 and cerium compounds. Calcite, aragonite, and vaterite appeared one after the other when increase the ethanol content in the case of CaCO3. While in the case of cerium compound, orthorhombic CeOHCO3, metalstable hexagonal CeOHCO3, and CeO2 formed as final product when decreasing the water content. The poor solubility of the inorganic materials in ethanol, and the size of the crystals decreasing with the increasing the content of ethanol, tend to formation of a kinetic phase.4. In acetone-water mixed solvents, nanostructured rutile TiO2 was synthesized. After a clean photoreduction process, M@TiO2 (M=Ag, Au, Pt) loaded with ultrathin metal nanoparticles were prepared without introduction of any toxic additives. Ag@TiO2 and Au@TiO2 nanocomposites show an excellent antibacterial ability. Pt@TiO2 nanocomposite presents a high photooxidation ability, which preformed oxidative polymerization of phenylenediamine, leading to the formation of a new kind of metal-semiconductor-conductive polymer hybrid materials.