Influence of different generations of PAMAM dendrimers on the crystallization of CaCO₃

The influence of different generation of poly (amidoamine) (PAMAM) dendrimers on the crystallization of CaCO₃ in aqueous solutions was studied. Crystallization of CaCO₃ in the presence and absence of half-generation PAMAM dendrimers was carried out. Crystals of CaCO₃ having different generations of dendrimers were analyzed by means of FTIR, XRD, SEM, respectively. The results show that the crystallization of CaCO₃ in the absence of dendrimer resulted in the formation of rhombohedral calcite crystals, and spherical crystals mixed of vaterite and calcite are formed in the presence of G-0.5, G-1.5, G-2.5 PAMAM dendrimers, and spherical varterite crystals are formed in the presence of G-3.5, G-4.5 PAMAM dendrimers. As the generation number of the PAMAM dendrimers increases from G-0.5 to G-4.5, the particle size of vaterite is decreased from (6.0±0.5)μm to (0.7±0.5)μm under the constant concentration of the -COONa unit of the PAMAM dendrimers.