Synthesis of hierarchical macro/mesoporous dicalcium phosphate monolith via epoxide-mediated sol-gel reaction from ionic precursors
Synthesis of hierarchical macro/mesoporous dicalcium phosphate monolith via epoxide-mediated sol-gel reaction from ionic precursors
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DOI：
10.1007/s10971-010-2184-y
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发表时间：
2011-03-01
影响因子：
2.5
通讯作者：
Hanada, Teiichi
中科院分区：
文献类型：
--
作者：
Tokudome, Yasuaki;Miyasaka, Akira;Hanada, Teiichi
以二水氯化钙（CaCl2 center dot 2H（2）O）、磷酸（H3PO4）和聚丙烯酸（PAA）为原料，在水和甲醇（MeOH）的混合溶剂中，通过加入环氧丙烷，合成了大孔和中孔共连续的无水磷酸二钙（DCPA，CaHPO4）整体材料。大孔是相分离的结果，而中孔是尺寸约为100 μ m的初级颗粒之间的空隙。30纳米。环氧丙烷用作质子清除剂，并导致反应溶液中的适度pH增加，这在几分钟内引起凝胶化。另一方面，PAA充当晶体生长抑制剂以及相分离诱导剂。DCPA的大量晶体生长受到PAA的阻碍，PAA的加入允许在微米范围内对结构进行形态控制。傅里叶变换红外光谱表明PAA与DCPA通过羧基与晶体表面的相互作用形成复合物，并共同形成凝胶相。在蒸发干燥后转化为大孔的溶剂相主要由溶剂组成。反应溶液中的过饱和度显著影响结晶过程，从而影响纳米和微米范围内的多孔结构。
Starting from calcium chloride dihydrate (CaCl2 center dot 2H(2)O), phosphoric acid (H3PO4), and poly(acrylic acid) (PAA) dissolved in a mixture of water and methanol (MeOH), dicalcium phosphate anhydrous (DCPA, CaHPO4) monoliths with co-continuous macropores and mesopores have been synthesized by the addition of propylene oxide. Macropores are formed as a result of phase separation, while mesopores as interstices between primary particles with the size of ca. 30 nm. Propylene oxide acts as a proton scavenger and leads to moderate pH increase in a reaction solution, which brings about gelation in several minutes. On the other hand, PAA acts as a crystal growth inhibitor as well as a phase separation inducer. The extensive crystal growth of DCPA is hindered by the addition of PAA which allows morphological control of the structure in micrometer range. Fourier transform infrared spectroscopy indicates that PAA and DCPA form composite via interaction between the carboxyl groups and the surface of crystals, and together form gel phase. The solvent phase, which is converted to macropores after evaporative drying, is mainly comprised of solvent. The degree of supersaturation in a reaction solution considerably influence on the crystallization process, and thereby, influences on the porous structure in nano- and micrometer ranges.