Preparation and Characterization of Nanocomposites Based on Poly(ε-caprolactone) and the Surface Grafted Nanohydroxyapatite with the Comb-shaped Poly(ε-caprolactone) Brushes

Surface modified hydroxyapatite/poly(ε-caprolactone) composites with comb-shaped poly (ε-caprolactone) (PCL) brushes grafted hydroxyapatite (n-HAP) were synthesized by a combination of atom transfer radical polymerization (ATRP) and ring-opening polymerization (ROP).,. Compared to the corresponding unmodified n-HAP/PCL composites, at modified n-HAP contents of 15 wt.% and 20% with a grafting ratio of 26.32%, the composites showed a maximum tensile modulus and elongation at break, flexural modulus and bending strength, respectively. This suggested that the comb-shaped PCL brushes at the interface are of advantage to the improvement of interfacial adhesion between the n-HAP and PCL polymer matrix by chain interdiffusion and entanglement with the PCL matrix. Furthermore, the observation should be attributed to the modified n-HAP particles, which were uniformly distributed in the polymer matrix and acted as heterogeneous nucleating agents during the crystallization of the PCL matrix.