Superstructures and Mineralization of Laminated Vaterite Mesocrystals via Mesoscale Transformation and Self-Assembly

Abstract

It is an interesting phenomenon for natural organisms to have control over the shapes and sizes of inorganic nanocrystals and arrange them into ordered superstructures. This phenomenon attracts many attempts to mimic the biomineralization process to synthesize novel materials. In the present work, a new superstructure of hexagonal vaterite mesocrystals consisting of nanocrystals has been synthesized via a mesoscale transformation process by controlled release of carbon dioxide through slow decomposition of dimethyl carbonate in the presence of cetyltrimethyl ammonium bromide at room temperature. The superstructures are composed of hundreds of well-stacked vaterite flakes, which build spheres with an axis and two poles. We can find that mesocrystal plates at the poles are arranged with their surfaces parallel to the axis, whereas the plates at the equator of the spheres are arranged with their surface vertical to their axes. The flakes present the unstable (001) planes and show hexagonal shapes with a thick core and thin edges. The subunits of vaterite flakes consist of oriented aggregation of nanocrystals which are transformed from the amorphous phase. New evidence of the mesoscale transformation process has been observed in detail by measuring the structures of the products at different reaction stages, revealing that the product evolves from amorphous oblate particles to doughnutlike particles, which crystallize and delaminate into superstructures. The mineralization process is discussed with the cooperative reorganization of coupled inorganic and organic components relevant for models of matrixmediated nucleation in biomineralization. This contribution will be helpful in understanding the aggregationdriven formation of complex and higher-order structured materials as well as the biomineralization mechanisms.

Sodium Lignosulfonate Induced Vaterite Calcium Carbonate with Multilayered Structure

“…As a comparison, the TGA curve of pure CaCO 3 without SL in Figure S3 of the Supporting Information only showed one weight loss of 44 %, when it was decomposed completely. This result is in agreement with the TG curve of CTAB–CaCO 3 composites42 and IR spectra. Under the present study, with increasing concentrations of SL in the range of 0.5–5.0 g L –1 , the weight loss of the obtained CaCO 3 at about 340–450 °C increased from approximately 2.2 to 4.7 %, thus indicating the increased content of SL in vaterite.…”

“…In addition, the hydrothermal reaction of calcium nitrate and urea affords a porous single‐crystalline and hexagonal prism‐shaped vaterite phase by means of nanocrystal aggregation in the presence of granular gelatin (a denatured protein with a high molecular weight) 41. More recently, well‐stacked laminated vaterite mesocrystals can be produced by using cetyltrimethylammonium bromide (CTAB) as surfactant, calcium chloride dihydrate as calcium source, and dimethyl carbonate as carbon source in a desiccator in which a beaker that contained ammonium hydroxide was placed at room temperature 42. Also, by adjusting the volume ratio of ethanol to water, the obtained vaterite crystals showed a multilayered cakelike shape, thus proving that solvent ethanol played an important role in stabilizing vaterite calcium carbonate polymorph, thereby preventing the transformation to thermodynamically more stable calcite 43.…”

Fast precipitation of uniform CaCO3 nanospheres and their transformation to hollow hydroxyapatite nanospheres

“…In order to fabricate calcium carbonate with desired crystallographic and morphological properties for tailored applications, the formation routes need to be controlled effectively. Over the past few decades, a substantial progress has been made in this field and many interesting phenomena have been unraveled which resulted in the formation calcium carbonate with intriguing shapes and properties [6][7][8][9][10][11][12]. In particular, the presence of organic additives such as surfactants, polymers, and biomolecules, during the mineralization process is found an important factor that influences the polymorph selection, nucleation and crystal growth.…”

Kalsiyum Karbonat Polimorflarının Oluşumuna Yaşlandırma Süresinin Etkisi

“…Literatürde farklı polimorf ve morfolojilere sahip CaCO 3 kristallerinin sentezi üzerine birçok çalışma bulunmaktadır. CaCO 3 kristalizasyonuna katkı maddesinin (Zhu et al 2009;Wei et al 2003), aşırı doygunluğun (Kawano et al 2002), pH'ın (Han et al 2006) ve sıcaklığın (Gopi et al 2013) etkisinin incelendiği çalışmalarda çalışma şartlarına bağlı olarak kararsız vaterit fazın kalsit faza dönüşümünün tamamen veya kısmen engellenebildiği görülmüştür.…”