原位自发泡制备磷酸钙/聚氨酯复合骨修复支架

磷酸钙/聚氨酯(CaP/PU)复合骨修复支架制备过程中随着材料体系粘度逐渐增大, 后期加入的发泡剂难于均匀分散, 影响支架孔隙率及孔结构均匀性。本研究在CaP/PU材料合成过程中将发泡剂水以磷酸氢钙结晶水合物(DCPD)的形式均匀复合在材料中, 在一定条件下释放结晶水与聚氨酯(PU)中的异氰酸根反应生成CO₂, 实现自发泡成型。实验结果显示, 90 ℃条件下自发泡制备的CaP/PU支架孔隙率高、孔结构均匀、贯通性好。将90 ℃发泡成型的CaP/PU多孔支架在110 ℃再熟化处理, 可提高支架的力学性能高达1倍以上。该方法简便易行, 为聚氨酯基多孔支架的制备提供了新思路。

Preparation of Calcium Phosphate/Polyurethane Composite Porous Scaffolds for Bone Repair by in situ Self-foaming Method

One of the main technical problems in preparation of calcium phosphate/polyurethane (CaP/PU) composite scaffold for bone repair is to obtain a porous structure with uniformly distributed pores. The reason for this is due to the heterogeneous dispersion of the added foaming agents within the composite resulting in the increasing viscosity of polymer precursor during the composite fabrication process. To solve this problem, we report a novel method through incorporation of calcium hydrogen phosphate (DCPD) with polymer phase to achieve a composite system in early period of the synthesis process of CaP/PU composite. The uniformly distributed crystal water from DCPD can be released when temperature reaches above 75 ℃ and serve as foaming agents to react with isocyanate group in the PU and generate CO₂ gas. The generation of gas leads to a self-foaming process and consequently induces CaP/PU composite to form a porous scaffold. Scanning electron microscopy (SEM) observations show that CaP/PU composite scaffolds with uniform porous structure, high porosity and interconnectivity were obtained at 90 ℃. The mechanical strength can be doubled by re-curing treatment for the scaffold at 110 ℃ for 24 h. The resulting CaP/PU composite scaffolds with uniformly porous structure, high porosity and interconnectivity have shown potential applications in bone tissue engineering. Moreover, this simple and efficient method may provide new approaches for the preparation of polyurethane- based porous scaffolds.