Supercritical carbon dioxide (SC-CO2) foaming technology was applied to fabricate highly porous poly(lactic acid-co-glycolic acid) (PLGA) scaffolds.The effects of polymer chemical composition (the mole percentage of glycolic acid in the polymer was 15 and 50 respectively)

molecular weight (50 kDa and 200 kDa) and the processing parameters including foaming pressure (from 10 MPa to 25 MPa)

temperature (from 35℃ to 85℃) and depressurization rate (0.05 MPa/s and 0.20 MPa/s) on the scaffold structure were investigated in detail.Morphologies of the scaffolds were characterized by scanning electron microscopy (SEM) and pore size distribution was obtained via analysis of SEM images.Porosity and interconnectivity of the scaffolds were measured by pycnometer (Archimedes principle) and mercury intrusion technique

respectively.The results showed that the pore size and interconnectivity increased while increasing the lactic acid content of the polymer.Higher pressure led to higher cell density and smaller pores

and pore coalescence occurred at low depressurizing rates.Glass transition temperature (Tg) of the polymer decreased under SC-CO2

and large polygonal cells were formed when the foaming temperature was set below 45℃.Differently

higher foaming temperature resulted in globular cells

with cell size decreased sharply.However

further increasing the temperature led to slightly larger pore sizes.Supercritical carbon dioxide foaming method makes it possible to fabricate the macro-cellular and micro-cellular foams of PLGA without using organic solvents and high temperature

which provide a way to fabricate porous polymer scaffolds for potential applications in tissue engineering.