Polymerization of D,L-lactide and in situ fabrication of PDLLA porous scaffolds in supercritical carbon dioxide

摘要

Poly(D,L-lactide) (PDLLA) was synthesized firstly by the ring-opening polymerization of D,L-lactide using tin(II) 2-ethylhexanoate as catalyst in supercritical carbon dioxide (scCO_2). Then, PDLLA porous scaffolds were prepared in situ by scCO_2 extraction/pore forming technologies. The structure and the molecular weight of PDLLA were characterized by FT-IR, ~1h NMR and GPC respectively. The porous structure morphology of the prepared scaffolds was observed by SEM. Results showed that PDLLA was synthesised successfully in scCO_2 fluid, and the molecular weight and yield of PDLLA were affected by reaction time, temperature and the concentration of catalyst. The best polymerization conditions were obtained as follows: reaction time of 48 h, temperature of 100° C and the concentration of catalyst of 0.1%. SEM results revealed that uniformly distributed and highly interconnected pore structures with a unique long gully type microstructure were formed in the PDLLA scaffolds.