Control the polymorphism and morphology of calcium carbonate precipitation from a calcium acetate and urea solution

Two metastable calcium carbonate polymorphs, rod-like aragonite and spherical vaterite are selectively formed in this study. Aragonite rods were synthesized from a calcium acetate (Ca(AC)(2)) and urea (CO(NH(2))(2)) solution under a given condition. In contrast, the addition of polyacrylamide (PAM) and oleic acid results in the formation of spherical vaterite. The morphology, size and crystal structure were characterized by means of Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and X-ray diffraction (XRD). The results show that PAM and oleic acid can be used as additives to select the polymorph from aragonite and vaterite. The contact angle of the modified products reached 112.49 degrees. We have succeeded in surface modification of particles in situ at the same time. (c) 2007 Elsevier B.V. All rights reserved.