Solubility controlled permeation of hydrocarbons in novel highly permeable polymers

► Membrane separation of binary mixtures CH4-C4H10. ► Dense films of Si-containing polynorbornene derivatives used as membranes. ► Solubility controlled permeation of gaseous alkanes was demonstrated. ► Concentration dependent increases in butane permeability. ► High permeability of butane and great selectivity of gas separation.