Hydrolytic degradation of polylactide/polybutylene succinate blends with bioactive glass

Polylactides (PLAs) have been vastly studied for biomedical engineering applications, but their rigidness limits their use. Blending them with more flexible polymers, such as polybutylene succinate (PBSu), results in softer materials, expanding the range of possible applications. However, the biopolymers lack bioactivity, which can be overcome by adding bioactive glass (BaG). Combining the inorganic phase with the organic phase (especially with blends) results in a complex material. Therefore, understanding the hydrolytic degradation of each component is crucial. In this context, we report on processing polylactide and polybutylene succinate (PLA/PBSu) blends and their composites (30 wt.% of bioactive glass 13-93, BaG). The impact of blending and compounding with BaG on the final product's molecular weight and mechanical properties and the BaG dispersion in the polymer matrices was assessed. In addition, in vitro degradation in PBS was studied. While the degradation of the polymer was assessed by GPC, the BaG dissolution was quantified by ICP-OES. Blending decreased the initial mechanical properties and molecular weight, and compounding with BaG further decreased the initial mechanical properties. During the immersion in PBS, blending accelerated the loss of mechanical properties and molecular weight, while BaG accelerated the degradation of PLA-containing materials but had little effect on PBSu. Blending and compounding with BaG enabled us to produce materials with a wide range of mechanical properties: bending strength of 34 – 125 MPa, shear strength of 22 – 47 MPa and bending modulus of 1.1 – 3.9 GPa. The selection of tailorable properties of these polymer/BaG composites enables their application for tissue engineering of bone to soft tissue.