反应pH值对原位水热沉积法制备纳米羟基磷灰石/壳聚糖复合材料的影响

Effect of pH value on the nano-hydroxyapatite/chitosan composites via in-situ hydrothermal precipitation

为避免羟基磷灰石(HA)在壳聚糖(CS)基体中分子出现分布不均的现象,在结合原位沉析法和水热法二者优点的基础上,发展了原位水热沉析法来制备HA/CS复合材料,并深入研究不同的反应pH值对该复合材料的影响。研究表明,在不同反应pH值下制备的复合材料,均由CS晶体和低结晶度的纳米HA晶体所组成,2种晶体均出现沿c轴方向上的择优生长。随着反应pH值的增大,复合材料中HA和CS分子的结晶度均增大,HA晶体尺寸增大,CS分子排列有序化程度增高,且二者之间发生较强的化学键合作用。当反应pH值增大到12时,复合材料中纳米HA的晶体尺寸约为27.63 nm,且均匀地分布在CS分子中;CS分子为高结晶度的α晶型,且分子排列规整,有序化程度高;存在于HA与CS分子间的化学键合作用最强。

In order to solve the distribution of hydroxyapatite （HA） in the chitosan （CS） matrix, a novel route of in-situ hydrothermal precipitation was developed to fabricate the nano- HA/CS composites, based on the combination of the advantages of in-situ precipitation and hydrothermal synthesis. The effect of pH value on the structure of the HA/CS composites was studied. All the results show that the as-prepared composites are composed of CS crystals and nano- HA with lower crystallinity, and the growth of CS crystals and HA crystallites is towards the preferred orientation along the c-axis in the crystal structure. Moreover, there is an increase of the crystallinity of CS and HA with the increase of pH value in the composites. It was noticed that the crystallite size of HA and the degree of the ordered arrangement of CS molecules are increased with raising the pH value in the composites. The pH value of 12 is favorable to the formation of the α-CS crystals with higher crystallinity and nano-HA crystallites in these composites. When the composites were prepared at the pH value of 12, there is a more ordered arrangement in the α-CS crystals and the good interaction behavior is found between CS molecules and HA crystallites in the composites.