The effect of hydroxyapatite (HA) particle shape on the reactivity of HA surfaces was investigated by selecting the rod‐shaped (r‐HA) and spherical HA particles (s‐HA) to coinitiate the ring‐opening polymerization of d,l‐lactide (DLLA) used stannous octoate (Sn(Oct)₂) as the catalyst, respectively. It was found that both s‐HA and r‐HA could be grafted with PDLLA and the reactivity of s‐HA was higher than that of r‐HA according to the results from FTIR, NMR, TGA and BET method. The potential mechanism was that the shape of HA particles determined the crystal faces exposed to participate in graft reaction clarified by performing X‐ray diffraction detections and Materials Studio analysis. The primary crystal faces were (211) and (112) for s‐HA yet (002) and (300) for r‐HA. These findings suggested that the shape of HA particles might influence their reactivity, which might provide a new way to improve the graft ratio of polymers so as to prepare HA/polymer composites with strong interfacial strength by selecting or designing the shape of the HA particles.

中文翻译：

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羟基磷灰石颗粒表面改性的反应性取决于其形状

通过选择棒状（r-HA）和球形HA颗粒（s-HA）共同引发d，l-丙交酯的开环聚合反应，研究了羟基磷灰石（HA）颗粒形状对HA表面反应性的影响。 （DLLA）使用辛酸亚锡（Sn（Oct）₂）分别作为催化剂。根据FTIR，NMR，TGA和BET方法的结果，发现s‐HA和r‐HA均可与PDLLA接枝，并且s‐HA的反应性高于r‐HA。潜在的机制是HA颗粒的形状决定了通过进行X射线衍射检测和Materials Studio分析所阐明的暴露于参与接枝反应的晶面。s‐HA的主晶面为（211）和（112），而r‐HA的主晶面为（002）和（300）。这些发现表明HA颗粒的形状可能影响它们的反应性，这可能为提高聚合物的接枝率提供了一种新的途径，从而可以通过选择或设计HA颗粒的形状来制备具有强界面强度的HA /聚合物复合材料。