Measurement of CO2 solubility and diffusivity in poly(l-lactide) and poly(d,l-lactide-co-glycolide) by magnetic suspension balance

The solubility of supercritical carbon dioxide (scCO2) in poly(l-lactide) and poly(d,l-lactide-co-glycolide) at different temperatures (308, 313 and 323 K) and pressures (10–30 MPa) was measured using a magnetic suspension balance. The solubility data were also used for estimating the binary diffusion coefficients. The results show a good solubility of CO2 in both polymers: up to 43% in poly(l-lactide) and 30% in poly(d,l-lactide-co-glycolide). The diffusion coefficients have high values, which verify the liquid-like solvating properties of scCO2. The diffusion coefficient depends on the quantity of gas already absorbed by the polymer; its values decrease with increasing gas concentration.