Cölfen H, Qi L
Max Planck Institute of Colloids and Interfaces, Colloid Chemistry, Potsdam, Germany.
Chemistry. 2001 Jan 5;7(1):106-16. doi: 10.1002/1521-3765(20010105)7:1<106::aid-chem106>3.0.co;2-d.
In this paper, a systematic study of the influence of various experimental parameters on the morphology and size of CaCO3 crystals after room-temperature crystallization from water in the presence of poly(ethylene glycol)-block-poly(methacrylic acid) (PEG-b-PMAA) is presented. The pH of the solution, the block copolymer concentration, and the ratio [polymer]/[CaCO3] turned out to be important parameters for the morphogenesis of CaCO3, whereas a moderate increase of the ionic strength (0.016 M) had no influence. Depending on the experimental conditions, the crystal morphologies can be tuned from calcite rhombohedra via rods, ellipsoids or dumbbells to spheres. A morphology map is presented which allows the prediction of the crystal morphology from a combination of pH, and CaCO3 and polymer concentration. Morphologies reported in literature for the same system but under different crystallization conditions agree well with the predictions from the morphology map. A closer examination of the growth of polycrystalline macroscopic CaCO3 spheres by TEM and time-resolved dynamic light scattering showed that CaCO3 macrocrystals are formed from strings of aggregated amorphous nanoparticles and then recrystallize as dumbbell-shaped or spherical calcite macrocrystal.
本文对聚（乙二醇）-嵌段-聚（甲基丙烯酸）（PEG-b-PMAA）存在下从水中室温结晶后各种实验参数对碳酸钙晶体形态和尺寸的影响进行了系统研究。溶液的pH值、嵌段共聚物浓度以及[聚合物]/[碳酸钙]的比例被证明是碳酸钙形态发生的重要参数，而离子强度适度增加（0.016 M）则没有影响。根据实验条件，晶体形态可以从方解石菱面体通过棒状、椭球状或哑铃状调整为球状。给出了一个形态图，该图允许根据pH值、碳酸钙和聚合物浓度的组合预测晶体形态。文献中报道的同一体系在不同结晶条件下的形态与形态图的预测结果吻合良好。通过透射电子显微镜（TEM）和时间分辨动态光散射对多晶宏观碳酸钙球的生长进行的更仔细研究表明，碳酸钙大晶体由聚集的无定形纳米颗粒串形成，然后再结晶为哑铃状或球状方解石大晶体。
