Fabrication and mechanical properties of PLLA/PCL/HA composites via a biomimetic, dip coating, and hot compression procedure.

Currently, the bone-repair biomaterials market is dominated by high modulus metals and their alloys. The problem of stress-shielding, which results from elastic modulus mismatch between these metallic materials and natural bone, has stimulated increasing research into the development of polymer-ceramic composite materials that can more closely match the modulus of bone. In this study, we prepared poly(L: -lactic acid)/hydroxyapatite/poly(epsilon-caprolactone) (PLLA/HA/PCL) composites via a four-step process, which includes surface etching of the fiber, the deposition of the HA coating onto the PLLA fibers through immersion in simulated body fluid (SBF), PCL coating through a dip-coating process, and hot compression molding. The initial HA-coated PLLA fiber had a homogeneous and continuous coating with a gradient structure. The effects of HA: PCL ratio and molding temperature on flexural mechanical properties were studied and both were shown to be important to mechanical properties. Mechanical results showed that at low molding temperatures and up to an HA: PCL volume ratio of 1, the flexural strain decreased while the flexural modulus and strength increased. At higher mold temperatures with a lower viscosity of the PCL a HA: PCL ratio of 1.6 gave similar properties. The process successfully produced composites with flexural moduli near the lower range of bone. Such composites may have clinical use for load bearing bone fixation.