Sorption of Gases and Vapors in an Amorphous Glassy Perfluorodioxole Copolymer

by V.I. Bondar and B.D. Freeman
Department of Chemical Engineering, North Carolina State University, 315 Riddick Hall, Raliegh, North Carolina 27695-7905

and Yu. P. Yampolskii
Institute of Petrochemical Synthesis, Russian Academy of Sciences, 29 Leninsky Pr., 117912, Moscow, Russia

Reprinted with permission from Macromolecules 1999,32, 6163-6171. Copyright 1999 American Chemical Society.

ABSTRACT

Gas and vapor sorption properties of a random copolymer of 87 mol % 2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxole and 13% tetrafluoroethylene (AF2400) are reported. Using both pressure decay and inverse gas chromatography (IGC) methods, a wide range of solutes was studied: He, N₂, O₂, CO₂, C₁-C₁₃ n-alkanes, CF₄, C₂F₆, C₆F₆, and C₆F₅CF₃. These solutes have critical temperatures ranging from 5 to 677 K. AF2400 has very large solubility coefficients, S, relative to other glassy and rubbery polymers. Only poly(1-trimethylsilyl-1-propyne), the most permeable polymer known, exhibits higher solubility coefficients. The large solubility coefficients in AF2400 are mainly due to high Henry's law solubility coefficients. Fluorocarbon solutes exhibit higher solubility than their hydrocarbon analogues. A novel linear correlation between the logarithm of S and T_c², where T_c is the solute critical temperature, was observed. On the basis of IGC results, the microcavity size in this perfluoropolymer is larger than in conventional hydrocarbon-based glassy polymers.


To view this article in its entirety, please see The American Chemical Society Publication, Macromolecules Volume 32, Number 19 pages 6163-6171 of September 21, 1999 or visit the website: http://pubs.acs.org/Macromolecules.