Polymeric scaffolds based on blends of poly-l-lactic acid (PLLA) with poly-d-l-lactic acid (PLA) prepared via thermally induced phase separation (TIPS): demixing conditions and morphology

Porous scaffolds based on blends of high crystalline Poly-l-lactic acid (PLLA) with low crystalline poly-d-l-lactic acid (PLA) were prepared via Thermally Induced Phase Separation (TIPS), with the aim of exploring the possibility to control the degradation behaviour of the PLA-based scaffold, simultaneously preserving the morphological characteristics required for tissue engineering applications. Porous foams with different PLLA/PLA weight ratios (from 95/5 to 60/40) were produced and characterised in terms of pore size, porosity, and thermal properties. The scaffolds present an open porosity, with average pore sizes ranging from 30 to 70 μm. Results showed that, when dealing with a PLLA/PLA blend, some relevant processing conditions of the preparation process (above all demixing temperature and total polymer concentration) must be carefully tuned, in order to attain suitable structures in term of pore size and porosity. In particular, with increasing amounts of PLA in a PLLA/PLA blend, the demixing temperature must be decreased and the overall polymer concentration decreased. Moreover, a preliminary investigation regarding the in vitro biodegradation rate of the blends was attempted, based on the determination of the crystallinity through wide angle X-ray diffractometry.