Structural and Mechanical Properties of Composite Scaffolds Based on Nano-hydroxyapatite and Polyurethane of Alcoholized Castor Oil

The interfacial interaction between two phases and homogeneous dispersion of inorganic phase in the organic matrix are critical factors for composite scaffolds with good structure and properties. Based on the modified soft-segment (alcoholized castor oil, ACO) of polyurethane (PU) and nano-hydroxyapatite (n-HA), porous n-HA/PU composite scaffolds were fabricated with in situ foaming method by controlling the process technology in this study. The results demonstrate that there exists good interfacial interaction between PU polymer matrix and polar n-HA due to increased hydroxyl number of modified polyurethane. Moreover, the n-HA filler can homogeneously disperse among the matrix and the miscibility is also dramatically improved. The micropore size of scaffolds is uniform, while the porosity, pore sizes and crystallinity are slightly decreased. FTIR and XRD analyses reveal that there are a large amount of hydrogen bond and chemical linkages between n-HA and ACO-PU matrix, which enhance the miscibility and stability of organic and inorganic phases. Correspondingly, the compressive strength and compressive modulus of scaffolds are significantly improved by alcoholized polyurethane and the uniformly dispersed n-HA particles. The nanocomposite scaffold can be used for further researches on regenerative medicine and bone tissue engineering.