Continuous structural evolution of calcium carbonate particles:: A unifying model of copolymer-mediated crystallization
Continuous structural evolution of calcium carbonate particles:: A unifying model of copolymer-mediated crystallization
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DOI：
10.1021/ja067422e
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发表时间：
2007-03-28
影响因子：
15
通讯作者：
Meldrum, Fiona C.
中科院分区：
文献类型：
--
作者：
Kulak, Alex N.;Iddon, Peter;Meldrum, Fiona C.
两种双亲水嵌段共聚物分别由一个非离子嵌段和一个由芳香磺酸基组成的阴离子嵌段组成，用作改性CaCO3结晶的添加剂。根据不同的反应条件，观察到CaCO3颗粒的明显形态变化。聚（环氧乙烷）-b-聚（4-苯乙烯磺酸钠）二嵌段共聚物对方解石颗粒的形态变化影响特别广泛，并且随着钙浓度的变化，产物颗粒从多晶到中晶再到单晶的连续结构转变被观察到。这种结构序列的存在为聚合物介导结晶的机理提供了独特的见解。我们认为它反映了结晶机制本身的连续性，跨越了从纳米颗粒的非定向聚集到经典的离子对离子生长的限制。形成多晶、中晶和单晶颗粒的各种途径，以前被认为是不同的，因此都形成了基于前驱体亚基聚集的统一结晶框架的一部分。
Two double-hydrophilic block copolymers, each comprising a nonionic block and an anionic block comprising pendent aromatic sulfonate groups, were used as additives to modify the crystallization of CaCO3. Marked morphological changes in the CaCO3 particles were observed depending on the reaction conditions used. A poly(ethylene oxide)-b-poly(sodium 4-styrenesulfonate) diblock copolymer was particularly versatile in effecting a morphological change in calcite particles, and a continuous structural transition in the product particles from polycrystalline to mesocrystal to single crystal was observed with variation in the calcium concentration. The existence of this structural sequence provides unique insight into the mechanism of polymer-mediated crystallization. We propose that it reflects continuity in the crystallization mechanism itself, spanning the limits from nonoriented aggregation of nanoparticles to classical ion-by-ion growth. The various pathways to polycrystalline, mesocrystal, and single-crystal particles, which had previously been considered to be distinct, therefore all form part of a unifying crystallization framework based on the aggregation of precursor subunits.