Effects of Porogen on Structure and Properties of Poly Lactic Acid/Hydroxyapatite Nanocomposites (PLA/HAp)

PLA/md-HAp/PEO porous nanocomposites for applications in bone engineering from poly lactic acid (PLA) incorporated with different NH4HCO3 porogen content were prepared by solvent casting method. The porosity, morphology and mechanical properties of the nanocomposites were determined. The obtained results showed that the porosity of the nanocomposites increases from 10 to 49% with the increase of NH4HCO3 porogen content from 0-30 wt%. However, their Young's modulus decreased 78% in comparison with the nanocomposite without using NH4HCO3 porogen. The bioactivity of the nanocomposite with 20 wt% NH4HCO3 porogen was evaluated by examining the formation of hydroxyapatite (HAp) on its surface when being immersed in simulated body fluids (SBF) solution. The in vitro degradation behavior of the nanocomposites immersed in the SBF solution at 37 Sc was systematically monitored at different time periods of 1, 3, 7, 14, 21 and 28 days. SEM images showed the formation of hydroxyapatite on the surface of the nanocomposite after 1 immersion day in the SBF solution. The measurements of weight loss, pH solution, and XRD of the samples indicated that PLA/md-HAp/PEO nanocomposite without NH4HCO3 porogen was degraded more slowly than the PLA/md-HAp/PEO nanocomposite with 20 wt% NH4HCO3 porogen.