Carbon Dioxide Sorption and Transport in Amorphous Poly(ethylene furanoate)

Abstract

Transport properties of carbon dioxide in amorphous poly(ethylene furanoate) (PEF) were investigated using complementary pressure-decay sorption and permeation techniques. Detailed measurements for PEF at 35 °C indicate a significant, surprisingly large reduction in carbon dioxide permeability of 19× at 1 atm compared to poly(ethylene terephthalate) (PET), despite both an increase in free volume and carbon dioxide solubility of 1.6× for PEF vs PET. The solubility increase for PEF, which originates from greater interaction between carbon dioxide and the polar furan moiety, is offset by a substantial reduction in diffusivity of 31× compared to PET. Such diffusion reduction for PEF, which is 3× greater than the 9.7× reduction in oxygen diffusivity compared to PET, is thought to originate from a hindrance of polymer ring-flipping motions compared to PET. A possible mechanism for the surprising barrier improvement for carbon dioxide in PEF vs PET is explained herein along with a detailed comparison to oxygen and water transport.