A Study On Biomimetic Synthesis Of CaCO₃ And Zn₄CO₃(OH)₆·H₂O Crystals Induced By Ordered Molecular Films

Study about oriented mineral crystal growth induced by Langmuir monolayers in the recent years has become a hot topic. A simple model surface was required in order to explore the organic-inorganic interface interaction and resolve some of molecular events mediating template-directed crystal nucleation and growth. With this in mind, Langmuir monolayer and LB monolayer were adopted us a planar two-dimensional matrix by spreading an insoluble amphiphile of the appropriate molecular design (headgroup identity, polarity, packing conformation) at the air-liquid interface, which could potentially mimic the surface of three-dimensional crystals and nucleation would be favored at the monolayer-solution interface. The growth of mineral crystals induced by Langmuir monolayers is different from that in bulk solution. It is general considered that crystal orientation during nucleation is determined by the special structure information of organic-inorganic interface, such as electrostatic interactions, lattice matching, stereo-chemistry matching, hydrogen bond, and so on. The principal advantage of monolayer model systems is that the composition of films and physical state of the interface can be controlled freely.In this work, the crystallization of CaCO3 and Zn4CO3(OH)6·H2O were investigated through LB technology. We analysised all of the results.The work we have carried out was as follows:1. Calcite Crystals Growth Was Induced By BSA LB film.We have investigated the growth of crystal CaCO3 using bovine serum albumin(BSA) LB monolayer film. At the same time, we studied the influence and control of the bovine serum albumin (BSA) LB film on the nucleation and growth orientation of calcium carbonate in the process of the biomineralization. The results of XRD show that the crystal grows only along the (104) and (208) manifests the clear edge and multilayer discoid crystal morphology. All the results suggest that BSA LB film can be used as a template to induce and regulate the calcium carbonate to crystallize with a special growth orientation and complex morphologies.2. Growth of Honeystructure-like ZnO film Induced by Bovine Serum Albumin Monolayer.We have synthesized honeystructure-like zinc carbonate hydroxide hydrate film was initially formed as assemblies on glass substrates by using the method of Biomimetic mineralization and Bovine Serum Albumin Langmuir film as the template at different surface pressure, subphase concentration and growth time. The Zn4CO3(OH)6·H2O film was transformed into wurtzite ZnO by heating at 400℃in air without losing the microstructure feature. We think that morphology of the film was largely influenced by BSA monolayer which presented in the solution.3. Growth of zinc carbonate hydroxide hydrate (Zn4CO3(OH)6·H2O) film Induced by benhenic acid(BA) Monolayer.We used the benhenic acid(BA) Langmuir monolayer as template to induce the zinc carbonate hydroxide hydrate film,compared with the experimental result of the last chapter and find that benhenic acid is not as bovine serum albumin as can be induced a dense honeystructure-like film. We speculate the interaction between the head group of the membrane material and metal ion as well as its own structural change were playing the very important role in the crystallization process by the membrane induced.