Sorption of vapours and liquids in PDMS: novel data and analysis with the GAB model of multilayer adsorption

• Sorption of vapours and liquids in PDMS.
• Application of the theory of multilayer adsorption – GAB.
• Oxygenated compounds – methanol, water, acetone, methanol derived ethers and esters.
• Energetics of sorption and diffusion.

Novel data on the sorption of vapours and liquids in cross-linked poly(dimethylsiloxane) (PDMS) elastomer at 25–40 °C are reported together with the accurate and original way of parameterising the sorption isotherms by using the GAB (Guggenheim, Anderson and De Boer) model of multilayer adsorption. The GAB model has been found to provide a comparable or better representation of sorption isotherms than the Flory–Huggins model with a concentration-dependent interaction parameter and better than the ENSIC (Engaged Species Induced Clustering) model. This comparison holds true for poor solvents of PDMS (water, methanol), mild solvents (acetone, methyl acetate, dimethyl carbonate) and good solvents (tert-butyl methyl ether, tert-amyl methyl ether, cyclopentyl methyl ether). The GAB model provided a noticeably good assessment of the sorption of liquids and highly saturated vapours, which makes the model applicable within the entire activity range.

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