Biomimetic Controlling of CaCO₃ and BaCO₃ Superstructures by Zwitterionic Polymer

In this work, uniform calcium carbonate (CaCO 3 ) and barium carbonate (BaCO 3 ) crystals were synthesized under the control of poly(2-methacryloyloxyethylphosphorylcholine) (PMPC) via a simple gas–liquid diffusion reaction. Spherical CaCO 3 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 BaCO 3, dumbbell-shaped crystals that were formed by the dendritic aggregation of rod-like subunits with six sides were generated. Both the morphologies of CaCO 3 and BaCO 3 crystals could be effectively tuned by changing the crystallization time and concentration of PMPC. Finally, a possible crystallization mechanism for the formation of CaCO 3 and BaCO 3 particles under the control of PMPC was proposed based on the experiments.