Sorption and diffusion of organic vapors in poly[bis(trifluoroethoxy) phosphazene] and poly[bis(phenoxy)phosphazene] membranes |
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| Institution: | 1. Boston Children''s Hospital, Boston, MA, USA;2. Harvard Medical School, Boston, MA, USA;3. Apogee Technology Inc., Norwood, MA, USA;1. Departament de Química Física, Universitat de València. C/ Dr. Moliner, 50, 46100, Burjassot, València, Spain;2. Sorbonne Universités, UPMC Univ Paris 06, UMR 8235, Laboratoire Interfaces et Systèmes Electrochimiques, F-75005, Paris, France;3. CNRS, UMR 8235, LISE, F-75005, Paris, France;1. Los Alamos National Laboratory, Los Alamos, NM, 87545, USA;2. University of California, Los Angeles, CA, 90095, USA |
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| Abstract: | The sorption isotherms and diffusivities for vapors of some selected simple alcohols (methanol, ethanol, isopropanol, and 2-butanol), ketones (acetone, methyl ethyl ketone, and methyl isobutyl ketone), and aromatic compounds (benzene, toluene, and xylene) in polybis(trifluoroethoxy)phosphazene] (PTFEP) and polybis(phenoxy)phosphazene] (PPOP) were determined by integral sorption-desorption experiments at 35°C. The sorption isotherms for these compounds evaluated were almost linear to obey Henry's law for the determination of constant solubility of each solvent vapor species, and the corresponding permeabilities for them can be estimated according to the solution-diffusion model. The diffusivities for these vapors in PPOP (10?9～10?8 cm2/s) were about one order smaller than those in PTFEP (10?8～10?7 cm2/s) because the more rigid phenoxy groups and the higher crystallinity in PPOP may hinder the diffusion of sorbed molecules. Relatively weak dependence of diffusivity or permeability on the vapor activity (or concentration) was found, to be in contrast to the exponential dependence for many organic vapors in rubbery organic polymers, probably due to the limited increase of the free volume in sorption for these vapors in PTFEP and PPOP membranes. |
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