Effect of molecular association on solubility, diffusion, and permeability in polymeric membranes

Abstract

The filling-type membrane is composed of grafted polymer and solvent-resistant substrate; the calculation of solubility, diffusivity and swelling-suppression effect by the substrate permits the prediction of solvent permeability. As noted in our previous article, the use of this approach, called membrane design, resulted in accurate prediction of the permeability of aromatic compounds. In this study, the influence of hydrogen bonding on solubility and diffusivity is investigated both theoretically and experimentally. The solubility of chloroform and dichloromethane in poly(acrylate)s increases, and their diffusivity decreases, compared with that estimated without considering the hydrogen-bonding effect. Solubilities predicted by the lattice-fluid hydrogen-bonding (LFHB) model show good agreement with the results of vapor sorption. Comparison of diffusion coefficients measured by vapor permeation with those predicted from free volume theory reveals that the decrease of solvent diffusion coefficient is approximately proportional to the fraction of associated molecules. Fluxes of chloroform and dichloromethane were measured by vapor permeation experiments through filling-type acrylate membranes, and predictions agree well with experiments.