Oriented Vaterite CaCO_3 Tablet-Like Arrays Mineralized at Air/Water Interface through Cooperative Regulation of Polypeptide and Double Hydrophilic Block Copolymer

摘要

Highly oriented vaterite CaCO3 tablet-like arrays were formed at the air/water interface through the cooperative mineralization regulated by polypeptide and double hydrophilic block copolymer under ambient conditions.The nearly parallel arrangement of CaCO3 vaterite tablets at the air/water interface shows the remarkable resemblance to the morphology of nacreous layers.The poly(aspartic acid) (PASP) with high molecular weight (M_w=11 000) and low solubility in water promoted the formation of vaterite tablets at the air/water interface,and stabilized the vaterite tablets by aggregation at the air/water interface and adsorption at the surface of vaterite tablets.Meanwhile,the highly hydrophilic poly(ethylene glycol)-block-poly(methacrylic acid) (PEG-b-PMAA) played an important role in regulating the arrangement and orientation of vaterite CaCO3 tablets,leading to the oriented tablet-like arrays at the air/water interface.Detailed experiments revealed that hydrophilic PEG-b-PMAA alone did not produce any form of CaCO3 crystals at the air/water interface,but could induce the formation of calcite CaCO3 particles in the water phase.However,high molecular weight PASP alone led to the formation of disk-like vaterite particles composed of helically aggregated nanoplates at the air/water interface,suggesting the regulating role of PEG-b-PMAA in the growth of vaterite tablet arrays.These results reported here provide a better understanding of the growth mechanism of nacreous layers and shells in nature.