Influence of methacrylate-containing surface modifiers on the mechanical properties of nano-hydroxyapatite/polylactide network composites

The influence of surface-coated nano-crystalline hydroxyapatite (nano-HA) on the mechanical properties of self setting nano-HA/polymer network composites was studied. Nano-HA was coated with the surface modifiers ethylene glycol methacrylate phosphate (EGMP) and bis[2-(methacryloyloxy)ethyl] phosphate (BIS-EGMP) prior to composite formation. The prepared composites were characterized by compression testing and scanning electron microscopy. The results revealed that the compressive strengths and Young's moduli were changed by coating nano-HA with different amounts of the surface modifiers. The toughness of the composites was considerably increased by coating nano-HA with EGMP resulting in a large plastic deformation of the composite before failure. In contrast, by addition of BIS-EGMP the ductile behaviour disappeared and the composites showed brittle behaviour. An explanation for these changes of the mechanical properties is given.