Prediction of solvent solubility, diffusivity and permeability in glassy polymeric membranes

The filling-type membrane is composed of grafted polymer and solvent resist ant substrate; calculation of solubility, diffusivity and the swelling-supp ression effect of a substrate enabled us to predict solvent permeability. T his approach, noted as membrane design, has previously been used in estimat ing permeability of aromatic compounds through rubbery polymeric membranes. In this study, the influence of plasticization on solubility and diffusivi ty is investigated theoretically and experimentally with poly(methyl methac rylate) (PMMA). Solubilities predicted by a group-contribution lattice-flui d equation of state (GCLF-EOS) model are consistent with the results of vap or sorption. A modified free volume model is proposed for calculating solve nt diffusion in glassy polymers by taking into account the compositional de pendence of depression on the glass transition temperature. The solvent dif fusion coefficient has a clear transformation at an isothermal glass transi tion concentration, and predictions are consistent with those measured by v apor permeation. Fluxes of benzene and toluene through filling-type PMMA me mbrane are measured by vapor permeation experiments, and it was found that the predictions agreed with the experiments. (C) 2001 Elsevier Science Ltd. All rights reserved.