Synthesis of hybrid linear-dendritic block copolymers with carboxylic functional groups for the biomimetic mineralization of calcium carbonate (original) (raw)
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Journal of Crystal Growth, 2007
The carboxyl group interacts strongly with calcium ions, indicating that the hydrophilic polymers with the functional groups of -COOH should exert a great impact on the crystal design of calcium carbonate (CaCO 3 ). In this paper, three copolymers were synthesized and subsequently used as additives to control the crystallization and aggregation behaviors of CaCO 3 . The results show that:
Polymer, 2007
A series of amphiphilic triblock copolymers poly(ethylene glycol)-block-poly(acrylic acid)-block-poly(n-butyl acrylate) (PEG-b-PAA-b-PnBA) differing only in the relative block lengths were synthesized by the acid-catalyzed elimination of the tert-butyl groups from poly(ethylene glycol)-block-poly(tert-butyl acrylate)-block-poly(n-butyl acrylate) (PEG-b-PtBA-b-PnBA), which was synthesized by atom-transfer radical polymerization (ATRP). The degree of polymerization, molecular weight and percentage of hydrolysis of the product PEG-b-PAA-b-PnBA were studied by gel permeation chromatography (GPC), NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS). Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to study the aggregation states of copolymers in water solution. The radii of the copolymer micelles shrink as Ca 2รพ is introduced into the solutions. The crystallization behaviors of calcium carbonate controlled by copolymer 1 (PEG 112 -b-PAA 86 -b-PnBA 60 ) and copolymer 2 (PEG 112 -b-PAA 40 -b-PnBA 72 ) differing mainly in the length of PAA block were systematically studied. It was found that the crystallization products are composed of calcite and vaterite, and the ratio of vaterite to calcite increases with increasing the concentration of copolymer 1. For copolymer 2, however, only calcite is obtained at all the concentration range investigated in this work.
Journal of Crystal Growth, 2008
This work concerns the use of different biopolymers such as chitosan, alginate or k-carrageenan as substrates to contribute to the study of the crystallization of calcium carbonate. The experimental biomimetic approach involves the preparation of mixtures of biopolymer solutions with a solution of CaCl 2 , which is processed by means of spin-coating and then exposed to CO 2 by a slow diffusion method for the growth of CaCO 3 . The obtained crystals show that each biopolymer has different effects on the crystallization habit. Different agglomerations of calcium carbonate crystals are initially the vaterite phase, which is subsequently stabilized as calcite. Biomineralization on each biopolymer gave rise to complex structures very different to those normally found in vitro, but similar to those observed in Nature. This confirms the strong influence of the macromolecules with ionizable groups on the stabilization of a determined polymorph and also on the morphology of the calcium carbonate crystals.
Polymer Engineering and Science, 2018
Crosslinked gelatin films with entrapped poly-L-aspartate were used to induce the crystallization of calcite and aragonite polymorphs. Calcite with high degrees of isomorphous substitution (up to 12 mol% magnesium) has been obtained. The morphology and laycred organization of magnesium calcite crystals grown inside the crosslinked gclatin films with entrapped poly-L-aspartate resemble some structural fcatures of radial calcitic ooids. The concentration of entrapped poly-L-aspartate and the uniaxial deformation of the films control the growth of aragonite aggregatcs inside the films. Such aggregates grown inside uniaxially deformed films consist of parallcl rods with an architectural assembly similar to Keywords aragonitebiomineralization * calcite * crystal growth
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007
The dendrite-shaped aragonite particles have been synthesized through the carbonation route, in which CO 2 gas is bubbled through aqueous slurry of calcium hydroxide, in the presence of polyacrylic acid (PAA) at high temperature. The as-prepared products were characterized with scanning electron microscope, X-ray diffraction and transmission electron microscope with selected area electron diffraction. It was found that the dendrite-shaped aragonite particle present the single-crystal feature. The effects of the reaction temperature and the concentration of PAA on the crystal polymorphs and morphologies of the as-prepared calcium carbonate were investigated. The results showed that both the organic additive and the reaction temperature turned out to be important parameters for the biomimetic synthesis of the dendrite-shaped aragonite particle. This research may provide new insight into the control of the polymorphs and morphologies of calcium carbonate.
Journal of the Brazilian Chemical Society, 2016
In this study, we report the synthesis of submicrometer calcium carbonate particles using the simplest approach of mixing solutions of calcium chloride and ammonium carbonate inorganic precursors in the presence of crystallization modifiers. Instead of the typical crystallization of CaCO 3 into large calcite crystals with rhombohedral morphology, very small uniform spherical vaterite particles were formed with the addition of small amounts of the anionic homopolymer poly(sodium 4-styrenesulfonate) (PSS). In contrast, large spheres made of a collection of calcite polycrystallite aggregates formed in the presence of poly(acrylic acid) (PAA). Crystal growth in a pre-organized environment created by the selective distribution of Ca II ions in the shell of polyestyrene-b-poly(acrylic acid) (PS-b-PAA) core-shell spherical micelles revealed a rather poor control of the size and morphology. Therefore, the PSS anionic homopolymer can be applied to the synthesis of submicrometer CaCO 3 particles from solutions of inorganic salts, which is a much cheaper and sustainable method than controlled CO 2 gas production and diffusion.
2015
In this study the role of PEG and PEO-PPO-PEO block copolymers molecular weight in precipitation of calcium carbonate was examined. The CaCO3 particles were characterized by FTIR spectroscopy, X-ray, SEM and particle size distribution analysis. In absence and presence of modifiers, mixing of the reagents led to the formation of calcite crystals. The calcium carbonate obtained with poly(ethylene glycol) and block copolymers was characterized by smaller diameter in comparison with the one without modifiers. It was observed that using compounds with different molecular weights has no obvious effect on the form and properties of precipitated calcium carbonate particles.
Water-Soluble Terpolymer-Mediated Calcium Carbonate Crystal Modification
Langmuir, 2004
The structure of the polymeric substrate plays an important role in the nucleation of calcium carbonate crystals. In this study a synthetic water-soluble poly (acrylamide-co-2-acrylamido-2-methyl-1-propane sodium sufonate-co-n-vinyl pyrrolidone) was found to be a substrate favouring the nucleation of polymorphs of calcium carbonate crystals under specific experimental conditions. Morphological characterization of the polymorphs was done using Atomic Force Microscopy, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, FTIR Analysis and X-ray Diffraction. If calcium carbonate is precipitated in the presence of terpolymer a remarkable increase in nucleation density (number of crystals per unit area) was observed. Stacked crystals of rhombohedral morphology were formed may be due to the presence of sodium sulfonate groups on the terpolymer. However, in the presence of poly-Laspartic acid, almost all crystals are hollow and have needle like or plate like morphology was formed. This change in calcium carbonate morphology can be explained by the variation of the polymer conformation, if poly-L-aspartic acid is present.