Study On The Process Of Pre-assembly Of Polyaspartic Acid For Biomimetic Synthesis Of Calcium Carbonate

Calcium carbonate biominerals has a complex topography and excellentperformance. So, it is an effective way to control the mineralization of calciumcarbonate in the synthesis of novel materials by learning the theory of biologicalmineralization. This paper used polyaspartic acid(PASP) as organic matter, which issimilar to biological protein. Proposed the pre-assembled template method bycombining the organic template theory and the existing methods of biomimeticminerialization and filtered assembly methods and optimized assembly conditions.Changed the crystallization conditions of pre-assembled template, explored the impactof the calcium carbonate polymorphs, morphology, analysis the formation and growthmechanism of the crystal. Here are the conclusions were reached:Contrasted with precipitation method and carbon dioxide access method, thecontent of vaterite had a significant increase. The time of mineralization had decreaseobviously, indicated that pre-assembled template method conducive PASP to formtemplate to control mineralization. Further filtered the pre-assembled model andoptimized the coditions,Used the ultrasound pre-assembly template method to synthetic calcium carbonateand change the condition of control crystallization factors. The vaterite content sharplyincreased and then slight declined, when the concentration is2.5mg/mL?the vateritecontent achieved maximum,92.52%, morphology changed from cubic particle tospherical, particle size declied from10um to1um. With the increase of supersaturation,the content of vaterit firstly increased and then declined, the spherical particle sizereduced and the cubic particle size increased, when the supersaturation index is6.75,vaterite content reached the maximum, and only spherical particles can be observed.Temperature rises conducive to the formation of vaterite phase, after40??the trend ofvaterite increasing become gentle, at80?, vaterite content reached the maximum96.24%, with the increase of temperature, the particle size declined from7-8um to about1um., the spherical particles formation take the advantage, in60-80?, the spherical particles assembled to long strip shape. Extend the dropping time of template solutionconducive to the content of vaterite increasing and the formation of spherical particles,continue to extend the dropping time after40min had little effect on crystalline andmorphology phase. The increase in the stirring speed can improve the content of vaterite,the content reach the maximum93.80%at500rpm. In the rage of0to100rpm, calciumcarbonate was divergent branches shpe. In the rage of200to500rpm, it's sphericalmorphology and well dispersed.The–COO-of PASP bond Ca2+to form template, the distance of both adjacent-COO-was matched to the12spatial configuration ligands of Ca2+, when nucleatehappens, CO32-replaced the location of–COO-of template and nucleate to vateriteaccording to12bit Ca2+conformation. The formation of template by PASP and Ca2+increase the supersaturation of microenvironment at organic-inorganic interface, it'sgood for inducing vaterite phase. the–COO-of PASP can combine with specific crystalplane in the minerialization process, durning the process, PASP play a play the role of abridge, make neighboring particles assembly and fusion to spherical morphology.