Study of the connectivity properties of Bioglass®-filled polylactide foam scaffolds by image analysis and impedance spectroscopy

The porous structure of two series of poly(d,l-lactide)/Bioglass® composite foams prepared by thermal-induced phase separation was investigated by image analysis and impedance spectroscopy. Polymer solutions of either low or high molecular weight containing different concentrations (up to 50 wt.%) of Bioglass® particles of mean particle size d < 5 µm were studied. The morphology of both macro- and micropores was studied by scanning electron microscopy and image analysis of both neat and composite foams (containing 10-50 wt.% Bioglass®). The pore connectivity of both neat polymer and composite foams was characterized by impedance spectroscopy in relation with their transport properties. The influence of the foam composition (i.e., polymer molecular weight and concentration of Bioglass®) on pore microstructure was studied using these non-destructive methods. It was found that addition of Bioglass® particles has a pronounced effect on pore orientation, leading to increasing loss of order of pore structure, especially for low-molecular weight PDLLA foams.