The Morphological Control Of Calcium Phosphate And Calcium Carbonate

The calcium phosphate and calcium carbonate as biological materials,which possess the same composition as biological hard tissue and exhibit potential applications in the field of biological probes,drug delivery and bone tissue engineering,attract more and more attention.Calcium phosphate and calcium carbonate with many forms of mineral phases,which exhibit different crystal phases and morphologies,are important for life activities.Hereinto,calcium phosphate and calcium carbonate with special shape and particular crystal phase exhibit unique superiority in the application.Therefore,the synthesis and control of calcium phosphate and calcium carbonate with special morphology and particular crystal phase were focused in the thesis,including calcium phosphate monolith with hierachical pore structure and vaterite phase calcium carbonate with regular hexagonal prism morphology.The calcium phosphate nanoparticles were synthesized by using calcium chloride and diammonium hydrogen phosphate at room temperature with the addition of NaOH to adjust pH of the reaction system.The calcium phosphate monoliths with hierachical pore structure were obtained by post-treatment of calcium phosphate nanoparticles at different conditions.The morphology,composition,crystalline phase and pore structure were characterized by SEM,FT-IR,XRD and N2-adsorption,respectively.The results showed that calcium phosphate monoliths exhibit hierachical pore structure with coexist of mesopores and macropores.The different post-treatment conditions directly affect the texture and pore structure of block materials,which cause the calcium phosphate to be controlled.In addition,the shape of the block materials could be regulated by selecting molds with different shape and size to meet the requirement of practical applications.The vaterite type calcium carbonate with regular hexagonal prism morphology was prepared by using calcium nitrate and urea with phenylphosphonic acid(PPA)as additive.The urea released carbonate ions and rose the pH value of the reaction system in the process of hydrothermal synthesis.The morphology,composition and structure of the products were characterized by SEM,FT-IR and XRD,respectively.The effects of phenylphosphonic acid as additive and the usage amount of urea on the products,as well as the formation mechanism of vaterite type calcium carbonate with hexagonal prism morphology were also investigated in detail.The outcome of the experiments indicated that the addition of PPA might control the speed of precipitation of calcium ions during the process of synthesis.The increase of pH value of the synthetic system oecurred with the usage amount of urea increasing,which caused the morphology,composition and crystalline phase of the products to change accordingly.Finally,the vaterite type calcium carbonate with regularly hexagonal prism morphology was obtained.The successful synthesis of calcium phosphate monolith and vaterite type calcium carbonate with regular hexagonal prism moqphology enriched the method of morphological control for bio-mineralization materials.The synthesis method for calcium phosphate monolith is generally applicable,while the synthesis of vaterite type calcium carbonate made up for the deficiency of natural vaterite mineral.Such two kinds of biological materials with special morphology would have potential applications in the field of biology and medicine.