Semi-permeable Membrane Under The Action Of Calcium Carbonate Preparation Of Biomimetic Materials

The significant difference between biomineralization and the general mineralization is that biomineralization produces inorganic minerals through the interactions between organic macromolecules and inorganic ions in the interface by the control of molecular lever. Biomimetic synthesis uses the biomineralization mechanism to produce inorganic materials making use of organic-assembly as templates, to control the formation of the inorganic minerals, and to prepare inorganic materials which have a unique micro-structure. The material has excellent physical and chemical properties. The study of Bionic calcium carbonate is to simulate biological environment, synthesize calcium carbonate crystals which are closer to the forms in the nature, and provide new methods for further in-depth understanding of the mechanism of mineralization and synthesizing new advanced composite materials.In this paper, CaCO₃ biomimetic materials were precipitated from Na₂CO₃/CaCl₂ reaction system, using semi-permeable membrane made from collodion as template to mimic the membrane in the bodies of the living creature. The samples were characterized by Fourier transform infrared spectroscopy(FTIR), X-ray diffraction(XRD) and scanning electronic microscopy(SEM). The influence on CaCO₃ of the membrane, surfactant, additives, the concentrations of the solutions and reaction time was considered. The obtained results were as follows:1. CaCO₃ was prepared using semipermeable membrane as template. With CaCl₂ solution in the membrane and Na₂CO₃ solution in the beaker, the metastable crystal vaterite was mainly obtained. Morphologies were dual-core and multi-core spherical particles, irregular ellipsoid, spindle-shaped particles and flower clusters of large irregular particles. Then with Na₂CO₃ solution in the semi-permeable membrane and CaCl₂ solution in the beaker, calcite crystals were mainly precipitated. Layered and irregular shape particles appeared.2. CaCO₃ was prepared when adding non-surfactant p-cyclodextrin(P-CD). The impact on CaCO₃ byβ-CD concentration and reaction time was studied. Nubbly and amorphous particles were immediately obtained after the solutions were mixed together. With 3 hours' stirring and with theβ-CD concentration increased, irregular blocks, ellipsoidal ball, overlapping multi-storey structure and regular smooth ball appeared. The presence ofβ-CD is conducive to the formation of calcite.3. CaCO₃ was prepared in the presence of both semipermeable membrane andβ-CD. The influence ofβ-CD concentration and the location of Na₂CO₃ and CaCl₂ was studied. With the CaCl₂ solution andβ-CD in membrane, both vaterite and calcite were prepared at the same time, but mainly vaterite. Morphologies were flower clusters, spherical particles and spindle-shaped particles. Then with the Na₂CO₃ solution andβ-CD in membrane and withβ-CD concentration increased, calcite was precipitated. Hexahedral and irregular shaped particles appeared.4. CaCO₃ was prepared in the presence of non-ionic surfactant Tween 80 and semipermeable membrane. With the CaCl₂ solution and Tween 80 in membrane, vaterite was mainly prepared. Then with the Na₂CO₃ solution and Tween 80 in membrane, calcite was mainly obtained. Crystal form didn't change obviously. It was a mixture of spherical and hexahedral particles.5. CaCO₃ was prepared in the presence of L-Glutamate(L-Glu) and semipermeable membrane. The influence of L-Glu concentration and the location of Na₂CO₃ and CaCl₂ was studied. Vaterite was mainly prepared. With L-Glu concentration increased, crystal form changed into different shapes, such as, blocks, spindle-shaped particles, petal-like layer structure, irregular spherical particles, wedge-shaped accumulation of small particles into the flower cluster and bulk band structure.The innovative points of this paper:1. CaCO₃ was prepared using semi-permeable membrane as template to imitate organisms growth process in the cell. The semi-permeable membrane is ion permeability, and as the time changes, a concentration gradient induced crystal nucleation growth.2. The influence of semipermeable membrane and non-surfactantβ-CD and the influence of semi-permeable membrane and non-ionic surfactant Tween 80 to the formation of CaCO₃ were researched.3. The preparation of CaCO₃ in the presence of both L-Glutamate(L-Glu) and semipermeable membrane was studied.