Composites of poly(l-lactide-trimethylene carbonate-glycolide) and surface modified calcium carbonate whiskers as a potential bone substitute material

Abstract

Calcium carbonate whisker (CCW) particles were surface modified by grafting of poly(L-lactide) (PLLA) chains in order to improve their affinity to a poly(L-lactide-trimethylene carbonate-glycolide) (PLTG) terpolymer matrix. Composites of the PLTG matrix with CCW and PLLA-g-CCW of various contents were prepared by mixing in solution followed by solvent evaporation. The structure and properties of pure CCW, surface modified PLLA-g-CCW and PLTG/PLLA-g-CCW composites were investigated using Fourier transfer-infrared spectrometry (FT-IR), mechanical testing, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), contact angle measurement, thermal gravity analysis (TGA) and differential scanning calorimetry (DSC). Data show that PLLA chains were successfully grafted on the CCW surface. The PLTG/PLLA-g-CCW composites exhibit a higher tensile strength and elongation at break than neat PLTG. Optimal values are obtained with a PLLA-g-CCW content of 2 wt%. It is assumed that PLLA-g-CCW particles present both reinforcing and toughening effects on the PLTG matrix. The cytocompatibility of the materials was evaluated from cell morphology and MTT assay using the L929 mouse fibroblast cell line. The results indicate that the composite presents very low cytotoxicity. Therefore, PLTG/PLLA-g-CCW composites with improved mechanical properties and good cytocompatibility could be promising as a potential bone substitute material.