Comparisons of the sorption and diffusion of supercritical carbon dioxide into polycarbonate and polysulfone

Diffusion and interaction of supercritical carbon dioxide (SCCO2) with polycarbonate (PC) and polysulfone (PSF) is investigated in this study. Experiments on the sorption of SCCO2 at 40 °C and 20 MPa into these polymers were carried out. Both the sorption amount of SCCO2 (Ms) and the desorption diffusivity (Dd) were determined by employing Fick's diffusion model. The Ms and Dd values for SCCO2 in PC were greater than those in PSF, owing to different interactions of SCCO2 with the polymers in the sorption process. The FTIR spectroscopy results for both polymers showed that CO2 desorbed faster from PSF than from PC. This indicated that the carbonyl group in PC had a stronger interaction with SCCO2. The plasticization effect of SCCO2 on these polymers was also investigated by comparing the DMA measurement results on pure and SCCO2 treated polymers. It is shown that PC had a larger shift in glass transition temperature than that of PSF after the SCCO2 treatment. This implied that there is a greater extent of plasticization on PC.