Measurement and correlation of diffusion coefficients of solutes in poly(Methyl methacrylate) under supercritical carbon dioxide

The self-diffusion coefficients of three solutes were measured in poly(methyl methacrylate) (PMMA) swollen by supercritical carbon dioxide (scCO₂) for fundamental research on supercritical impregnation technology. Anthraquinone, 2-methyl anthraquinone, and disperse red 1 were selected as the solutes. UV-visible spectrophotometry was used to measure the absorbance of the solutes impregnated into the PMMA film. Fick’s second law of diffusion was applied to calculate the diffusion coefficients of the solutes. The diffusion coefficients were measured in the range 10–21 MPa and 313.2–333.2 K. The experimental diffusion coefficient data for the solutes are correlated well with the free volume theory.