Calcium carbonate crystallization in tailored constrained environments

Abstract

a Synthesis of inorganic particles using routes inspired by biomineralization is a goal of growing interest.Recently it was demonstrated that the size and geometry of crystallization sites are as important as the structure of charged templating surfaces to obtain particles with controlled features. Most biominerals are formed inside restricted, constrained or confined spaces where at least parts of the boundaries are cell membranes containing phospholipids. In this study, we used a gas diffusion method to determine the effect of different lecithin media on the crystallization of CaCO 3 and to evaluate the influence of the spatial arrangement of lecithin molecules on templating CaCO 3 crystal formation. By using inorganic synthesis, Raman spectroscopy, dynamic light scattering, electrochemical methods and scanning electron microscopy, we showed that the occurrence of surface-modified calcite crystals and diverse textured vaterite crystals reflects the geometry and spatial distribution of aqueous constrained spaces due to the lecithin assembly controlled by lecithin concentration in an ionized calcium chloride solution under a continuous CO 2 diffusion atmosphere. This research shows that by tailoring the assembly of lecithin molecules, as micelles or reversed micelles, it is possible to modulate the texture, polymorphism, size and shape of calcium carbonate crystals.

Functionalized Multiwalled CNTs in Classical and Nonclassical CaCO3 Crystallization

“…A set of GD crystallizations of CaCO 3 was performed in triplicate at 24 °C over 24 h to evaluate the effect of all MWCNT additives on the nucleation and crystal growth of CaCO 3 [25,26,27]. As shown in Figure 2a–d, different CaCO 3 morphologies were obtained in the presence of pristine, oxidized, and functionalized MWCNTs during the crystallization.…”

Crystallization in Confinement

“…Biomineralization processes invariably occur within privileged environments, where an organism can define and localize where mineralization occurs, and exert control over mineralization, for example, by introducing different soluble additives at different time points. Liposomes (vesicles bounded by a phospholipid membrane) provide a convenient model of biomineralization systems, and have often been used as environments to precipitate materials such as calcium carbonate, [198,199] iron oxides, [200][201][202] and calcium phosphate. [203][204][205] The cations are typically encapsulated within the liposomes, and precipitation is then initiated either by diffusion of a gaseous reagent across the lipid bilayer or through a pH change in the bulk medium.…”

From Solute, Fluidic and Particulate Precursors to Complex Organizations of Matter

“…The integration of heterogeneous constituents into nanostructured composites is also achieved by combining the nucleation and assembly of particles under the influence of macromolecules. Based on their chemical functionality, molar mass and molecular organization, macromolecules serve multiple functions including (i) the confinement of the reactants directing emergent particle shapes, sizes, polymorphs and textures,, (ii) the stabilization of high energy surfaces of nanocrystals and (iii) the introduction of long range order to particle assemblies . This approach is exemplified by the synthesis of layered double hydroxides (LDHs) intercalated with polysaccharides (Figure c).…”