(566a) Energetics of Condensable Gas Transport in Poly(arylene ether) Random Copolymers

Preliminary data has shown that microporous polymers, including poly(arylene) ethers, can be promising materials for condensable gas separations, such as hydrofluorocarbon refrigerant reclamation¹ and carbon dioxide purification from industrial off-gas^2-4. However, industrial use of these materials remains challenging due to several issues including physical aging, which can hinder diffusion-driven separation performance, ^1,5 and plasticization⁶, when condensable gases dissolve into the polymer resulting in accelerated segmental motions and decreased size-sieving. In this talk, sorption and permeability results are reported for a series of triptycene-poly(arylene ethers) (PAEs) for CH₄, CO₂, CH₂F₂, and CF₄. Using the dual-mode model and pure-gas permeation experiments, the solubility and diffusivity effects were deconvoluted to determine the mechanism of sorption and sorption-selectivity. Observed improvements in sorption selectivity for the non-fluorinated and partially fluorinated polymers were found to result primarily from increased Langmuir sorption selectivity. Preliminary analysis of energetics indicates that fluorination does not appear to affect bulk penetrant-polymer mixing as strongly as fractional free volume. Finally, CO₂/CH₄ sorption selectivities are reported far above unity, indicating a method to increase sorption selectivity for condensable gas separations.

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