Aqueous precipitation of calcium carbonate modified by hydroxyl-containing compounds

Calcium carbonate was grown from aqueous solution in the presence of organic crystal modifiers of the saccharide and alcohol subclasses. The control crystallization procedure preferentially nucleates vaterite, the kinetically stabilized calcium carbonate polymorph. Addition of saccharides (mono-, di-, and polysaccharides) to the crystal mix drives the system to nucleate calcite, the thermodynamically preferred polymorph. However, the degree of calcite stabilization for the monosaccharides is modified by the number of equatorial -OH moieties. Disaccharide results were not a simple addition of the individual component behaviors. Deviation firom rhombohedral calcite was only observed for amylose, producing crystals elongated along the c-axis. The mixed saccharide/alcohol series gave results comparable to the addition of saccharide alone. The alcohol acted only to displace the observed saccharide trend to lower saccharide concentrations. Hence, saccharide additives dominate both nucleation and growth of calcium carbonate and act principally to drive the system to thermodynamic nucleation.