Synthesis of Submicrometer Calcium Carbonate Particles from Inorganic Salts Using Linear Polymers as Crystallization Modifiers

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 CaCO3 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 CaCO3 particles from solutions of inorganic salts, which is a much cheaper and sustainable method than controlled CO2 gas production and diffusion.