Crystal Design of Calcium Carbonate Microparticles Using Double-Hydrophilic Block Copolymers

Abstract

Small block copolymers, consisting of a hydrophilic poly(ethylene glycol) block and a second hydrophilic moiety which strongly interacts with alkaline earth ions, were employed to template the precipitation of calcium carbonate from aqueous solution. Depending on the type of polymeric functionalization pattern used, it was possible to grow two of the three different crystal modifications of CaCO3 (vaterite and calcite) under similar conditions. Vaterite could be successfully stabilized for more than 1 year by the polymer under conditions where it would normally transform into calcite within 80 h. Also the crystal size and shape respond to the polymeric template; for example, it was possible to grow monodisperse spherical particles with a diameter of ca. 2 μm or hollow spheres both consisting of aggregated nanocrystallites. The effect of different functional groups and of variable block length on the size, shape, and morphology of CaCO3 is discussed. It must be emphasized that these particles sediment, but are stabilized and protected by a dense layer of double-hydrophilic block copolymers, which enables direct use as pigments and fillers or in ceramic processing.

Shape Controlled Synthesis of Barium Carbonate Microclusters and Nanocrystallites using Natural Polysachharide – Gum Acacia

“…The crystallization involves the formation of different hierarchical structures like rods through dumbbell to flower shaped which have never been seen before in natural biominerals. Proteins and polysaccharides with complicated patterns of various functional groups in GA selectively adsorb on to the metal ion thereby hindering the crystal growth, followed by the mesoscale self-assembly of nanometer-scale building block into hierarchial superstructures [38][39][40][41][42]. The key reaction of CO 2 with Ba 2+ ions entrapped within GA polymer leads to the growth of beautiful structures of witherite nanocrystalline, such an aggregated morphology not normally observed using other surfaces as templates.…”

Nanostructured silica templated by double hydrophilic block copolymers with a comb-like architecture

“…The new strategy consists in replacing the classical amphiphilic template by an induced and reversible assembly of watersoluble block copolymers (WSBC) [13][14][15], which allows to recover the template in aqueous solution. The micellization [16][17][18] process results from electrostatic interactions between two oppositely charged polymers in aqueous solution, a hydrophilic polyelectrolyte-neutral diblock copolymer and a homopolyelectrolyte.…”

Template‐Dependent Morphogenesis of Oriented Calcite Crystals in the Presence of Magnesium Ions

“…[9][10][11] Numerous in vitro studies, in which calcite growth was modified by the interaction with various organic and inorganic solution additives, have reported the formation of crystals with diverse morphologies. [4,[12][13][14][15][16][17][18][19][20] Although these experiments were successful in demonstrating the ability to alter the morphology of calcite from its regular {104}-cleavage rhombohedron form, the modified crystals were, in general, heterogeneous in their shapes, sizes and orientations.…”