Surface and statistical analysis of CaCO3 crystals synthesized in the presence of fluorescein-tagged starch grafted with polyacrylic acid

Crystallization of CaCO3 was carried out in the presence of fluorescein-tagged starch grafted with polyacrylic acid (PAA) as polymeric additive. The crystal morphology at high polymeric additive concentration was spherical, with vaterite and calcite polymorphs. Mixed crystal morphologies were obtained at lower concentration of the polymeric additive and calcite was obtained. The CaCO3 crystals obtained fluoresced under UV irradiation showing the presence of grafted starch expected on the surface of CaCO3. The zeta potentials of the synthesized crystals were negative and addition of cationic starch lead to inversion of the zeta potential. Rodamine B-tagged cationic starch was successfully deposited onto the surface of the anionic-grafted starch-coated CaCO3 crystals. Statistical analysis of the crystals showed that the fluorescence intensities of the crystals increased with increasing granularity and size of the CaCO3 crystals. The high granularity and large-size crystals were due to aggregation of secondary crystals as observed with fluorescence microscopy.