Biomimetic Controlling of CaCO3 and BaCO3 Superstructures by Zwitterionic Polymer

In this work, uniform calcium carbonate (CaCO3) and barium carbonate (BaCO3) crystals were synthesized under the control of poly(2-methacryloyloxyethylphosphorylcholine) (PMPC) via a simple gas liquid diffusion reaction. Spherical CaCO3 particles with six smooth facets symmetrically distributed on the surface were prepared and systemically characterized by means of TEM, SEM, XRD, Raman, TGA, and FTIR. Time-resolved experiments showed the spherical calcite crystals were transformed from amorphous calcium carbonate (ACC) in the early stage and underwent a dissolution-recrystallization process in the later stage. For BaCO3, dumbbell shaped crystals that were formed by the dendritic aggregation of rod like subunits with six sides were generated. Both the morphologies of CaCO3 and BaCO3 crystals could be effectively tuned by changing the crystallization time and concentration of PMPC. Finally, a possible crystallization mechanism for the formation of CaCO3 and BaCO3 particles under the control of PMPC was proposed based on the experiments.