Chain-Folding Effects on Polymer Film Gas Permeabilities

Polymer gas sorption and permeability are key parameters when choosing materials for applications from gas separation to food packaging. These parameters are naturally affected by the polymer chemistry, but also by the bulk morphology. In this work, the effect of chain folding (intramolecular) collapse on such properties is studied. While maintaining the same chemical composition, powders and films made from linear and folded chains are compared, indicating that chain folding affects only slightly the overall gas solubility in the polymer, but the diffusivity and permeability is changed very significantly. Measurements at different pressures provide clear support for well-behaved systems which are chemically similar but show very different properties, allowing for the decoupling of chemistry and properties.