The effect of simulated body fluid on the mechanical properties of multiblock poly(aliphatic/aromatic-ester) copolymers.

The effects of simulated body fluid (SBF) on the surface and mechanical properties of poly(aliphatic/aromatic-ester) (PED) copolymers were investigated. PED copolymers containing different hard (aromatic) and soft (aliphatic) segment weight ratios were exposed to SBF for 52 days, and afterwards their mechanical properties were evaluated. A quasi-static tensile test estimating relaxation and fatigue properties from the hysteresis method was performed. The surface properties were monitored with scanning electron microscopy and energy-dispersive X-ray spectrometry. PED copolymers showed various susceptibilities to apatite layer formation on the surface. This was ascribed to the hard/soft segment ratios of PED materials. Polymers containing higher amounts of amorphous soft segments showed a better deposition with the apatite layer, which provided improved mechanical properties, especially fatigue (improved dynamic creep resistance).