Kinetic and equilibrium sorption of organic liquids and vapors in Matrimid

Abstract This work examines the kinetic and equilibrium sorption characteristics of a variety of chemical penetrants in the polyimide polymer Matrimid. Liquid equilibrium sorption for dense films with thicknesses of 50 µm for a large variety of organic species including alkanes, alcohols, acetates, furans, and ionic liquids is presented. Vapor equilibrium sorption isotherms and kinetic sorption behavior for water and C1-C6 alcohols as a function of chemical activity from 0 to 0.9 were measured using a quartz crystal microbalance with films ranging in thickness from 0.07 to 2.0 µm. Diffusion coefficients and relaxation parameters were calculated according to the diffusion-relaxation model for penetrants in glassy polymers. Diffusion coefficients at infinite dilution for water and C1-C6 alcohols are given as a function of van der Waals molar volume and a clear dependency is shown ranging from 2E-11 to 6.5E-13 cm 2 /s for water and hexanol, respectively, for 0.26 µm thick films. Diffusion coefficients for all studied vapor penetrants displayed a marked dependence on thickness spanning approximately two orders of magnitude for each respective vapor penetrant over the range 0.1–1.0 µm. Penetrant-induced relaxation behavior accounts for the majority of mass sorption at chemical activities of 0.2 and above for the C1-C6 alcohol vapors.