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 (scCO2). Then, PDLLA porous scaffolds were prepared in situ by scCO2extraction/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 scCO2fluid, 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.
An In Situ High-Pressure NMR Study of Hydrogen Bonding of Alcohols in Supercritical Carbon Dioxide.