Chang Myung Chul, Douglas William H, Tanaka Junzo
School of Mat. Sci. and Chem. Eng., Kunsan National University, Kunsan 573-701, Korea.
J Mater Sci Mater Med. 2006 Apr;17(4):387-96. doi: 10.1007/s10856-006-8243-9.
The crystal development of hydroxyapatite[HAp] phase in gelatin[GEL] matrices was investigated in the temperature range 37 to 80 degrees C by using X-ray diffraction, scanning electron microscopy(SEM), thermoanalytical measurement(DT/TGA), Fourier-Transformed Infra-Red(FT-IR) spectroscopy, and transmission electron microscopy(TEM) with electron diffraction(ED). It was found that during the coprecipitation of apatite phase in GEL matrices and the next aging process the crystallites were formed and developed through the two reaction mechanisms of organic-inorganic interaction between apatite phase and GEL molecules, and thermodynamic reaction for the crystal growing. The analytical evidences showed that there was a definite competition between these two mechanisms with the reaction temperature. Below 50 degrees C the crystal development of HAp was greatly suppressed by the existence of the GEL molecules, indicating the heterogeneous nucleation by the supposed number of carboxyl groups in GEL. Above 50 degrees C the effective organic components as a template for the heterogeneous nucleation of apatite crystallites were greatly degraded and so more amount of inorganic ions could be favorably accredited on the preexisting crystallites in virtue of the limited nucleation chance, finally resulting in the crystal growth. At higher temperature pretty big HAp crystals were developed with the depletion of the organics to be bound with crystallites in the slurry solution. Presumably it is believed that the poisoning of the functional groups in GEL molecules was vigorously occurred in the phosphoric acid environment above approximately 50 degrees C.
通过X射线衍射、扫描电子显微镜（SEM）、热分析测量（DT/TGA）、傅里叶变换红外（FT-IR）光谱以及带有电子衍射（ED）的透射电子显微镜（TEM），研究了明胶（GEL）基质中羟基磷灰石[HAp]相在37至80摄氏度温度范围内的晶体生长情况。研究发现，在GEL基质中磷灰石相的共沉淀过程以及随后的老化过程中，微晶通过磷灰石相和GEL分子之间的有机-无机相互作用以及晶体生长的热力学反应这两种反应机制形成并生长。分析证据表明，这两种机制在反应温度方面存在一定竞争。低于50摄氏度时，GEL分子的存在极大地抑制了HAp的晶体生长，这表明GEL中假定数量的羧基导致了异质成核。高于50摄氏度时，作为磷灰石微晶异质成核模板的有效有机成分大量降解，因此由于成核机会有限，更多的无机离子能够有利地附着在预先存在的微晶上，最终导致晶体生长。在较高温度下，随着浆料溶液中与微晶结合的有机物的消耗，形成了相当大的HAp晶体。据推测，大约50摄氏度以上的磷酸环境中，GEL分子中的官能团会剧烈中毒。
