Influence of the Nature of Chemical Modification of Addition Poly(5-vinyl-2-norbornene) on the Gas Permeability of Hydrocarbons

The gas permeability of hydrocarbons (CH₄, C₂H₆, n-C₄H₁₀) through four polynorbornenes obtained by modification of the addition poly(5-vinyl-2-norbornene) is studied. Upon modification, both polar (oxirane and thioacetyl fragments) and nonpolar substituents (cyclopropyl and ethyl groups) are introduced into side substituents. The introduction of polar groups leads to a decrease in gas permeability, while the hydrogenation or cyclopropanation of addition poly(5-vinyl-2-norbornene) causes an increase in gas permeability. Despite the fact that the synthesized polymers are glassy and nonmicroporous materials, they have an unusual feature for such polymers—the selectivity of hydrocarbon separation controlled by solubility (α(n‑C₄H₁₀/CH₄) ≫ 1). Among the studied polymers, the optimal combination of gas permeability and selectivity is observed for the cyclopropanated polymer.