Macroscopically ordered polymer/CaCO3 hybrids prepared by using a liquid-crystalline template
Macroscopically ordered polymer/CaCO3 hybrids prepared by using a liquid-crystalline template
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DOI：
10.1002/anie.200705062
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发表时间：
2008-01-01
影响因子：
16.6
通讯作者：
Kato, Takashi
中科院分区：
文献类型：
--
作者：
Nishimura, Tatsuya;Ito, Takahiro;Kato, Takashi
生物矿物是由生物体在温和条件下形成的有机/无机杂化物。[1-3]生物大分子，如多糖，蛋白质和糖蛋白作为模板，控制晶体生长的生物矿物，从而导致形成高度组织的混合结构。[1-3]最近，密集的工作一直集中在基于碳酸钙的生物矿化启发的杂化材料的开发。[1-14]为了制备这些表现出多种性能的新型杂化材料，如机械稳定性，光学性能和生物功能性，[11]必须在宏观尺度上控制无机和有机组分的取向和结构。然而，这种对组分的取向和形态的控制还没有有效地实现。我们的目的是获得高度组织的杂化材料，使用宏观有序的模板的液晶（LC）大分子。在这里，我们报告的有序聚合物/碳酸钙杂化材料的制备通过使用宏观有序的LC状态的半合成甲壳素衍生物作为模板。只有一对夫妇的研究使用有序矩阵已被报道，这些矩阵来自生物系统。[12 Mann及其同事证明了使用从海螵蛸获得的宏观有序的β-几丁质基质形成有序的多孔几丁质/二氧化硅复合材料。[15]Falini及其同事使用从鱿鱼圈中获得的定向β-甲壳素作为钙盐的基质，从而形成定向晶体。[12]如果我们能够利用和控制合成或半合成聚合物基体的有序化过程，就可以更容易地获得各种自组织的杂化宏观结构。在薄膜CaCO 3晶体的形成中，矿物质在酸溶性大分子存在下沉积在固体聚合物基质上。[4，10]固体基质如多糖和聚乙烯醇与酸性大分子的配合对于形成混合薄膜结构是必不可少的。[10]我们先前报道了在存在从小龙虾外骨骼分离的酸性天然肽的情况下，在随机取向的几丁质基质上形成CaCO 3的单向取向薄膜晶体。[13]然而，这些薄膜的尺寸只有10 - 10 μm，每个膜的取向方向是随机的宏观尺度上，因为随机排列的甲壳素矩阵。此外，需要具有特定氨基酸序列的酸性肽。我们的方法是使用LC模板获得高度有序的混合物。液晶可以在宏观尺度上形成取向分子的大畴。[17]我们预计，取向的聚合物固体基质处理通过其LC状态应作为模板诱导碳酸钙的单向晶体生长。有序甲壳质基质通过甲壳质氨基甲酸酯化获得的相应LC甲壳质衍生物[18]的加工和脱保护制备（图1）。甲壳素苯基氨基甲酸酯形成了一种溶致
Biominerals are organic/inorganic hybrids formed by living organisms under mild conditions.[1–3] Biomacromolecules such as polysaccharides, proteins, and glycoproteins serve as templates that control the crystal growth of biominerals and thus result in the formation of highly organized hybrid structures.[1–3] Recently, intensive work has been focused on the development of biomineralization-inspired hybrid materials based on CaCO3.[1–14] For the preparation of these novel hybrid materials exhibiting versatile properties such as mechanical stability, optical properties, and biofunctionality,[11] it is essential to control the orientation and structure of both inorganic and organic components on the macroscopic scale. However, such control over orientation and morphology of the components has not yet been effectively achieved. Our intention was to obtain highly organized hybrid materials using macroscopically ordered templates based on liquidcrystalline (LC) macromolecules. Herein we report on the preparation of ordered polymer/CaCO3 hybrids by using the macroscopically ordered LC states of a semisynthetic chitin derivative as template. Only a couple of studies on the use of ordered matrices have been reported, and these matrices were derived from biosystems.[12, 15, 16] Mann and co-workers demonstrated the formation of ordered porous chitin/silica composites using a macroscopically ordered β-chitin matrix obtained from cuttlebone.[15] Falini and co-workers used the aligned β-chitin obtained from the pen of a squid as a matrix for calcium salts, which resulted in the formation of oriented crystals.[12] If we could use and control the ordering processes of synthetic or semisynthetic polymer matrices, a variety of self-organized hybrid macroscale structures could be obtained more easily. In the formation of thin-film CaCO3 crystals, the minerals are deposited on solid polymer matrices in the presence of acidic soluble macromolecules.[4, 10] Cooperation of solid matrices such as polysaccharides and poly-(vinyl alcohol) with acidic macromolecules is essential to form hybrid thin-film structures.[10]We previously reported on the formation of unidirectionally oriented thin-film crystals of CaCO3 on a randomly oriented chitin matrix in the presence of an acidic natural peptide isolated from the exoskeleton of a crayfish.[13] However, the size of these thin films was only 10 10 μm and the direction of orientation of each film was random on the macroscopic scale because of the random arrangement of the chitin matrix. Furthermore, acidic peptides having specific sequences of amino acids were required. Our approach here is to obtain highly ordered hybrids using LC templates. Liquid crystals can form large domains of oriented molecules on the macroscopic scale.[17] We expected that oriented polymeric solid matrices processed through their LC states should serve as templates to induce unidirectional crystal growth of CaCO3. The ordered chitin matrix was prepared by processing and deprotection of a corresponding LC chitin derivative [18] obtained by carbamation of chitin (Figure 1). The chitin phenylcarbamate formed a lyotropic