he permeability coefficients of six different ODPA-based polyethermide membranes to H2

CO2

O2

N2

and CH4. have ho measured at 0. 7 MPa and at temperatures from ambient up to 150 ℃. Systematic variations in chemical structure were found to lead to sighficant changes in permeability coeffidents and ideal separation factors of polyetherimide membranes. Among the six polyetherimdes

ODPA-IPDA with the largest free-volume and larger intrasegmental mobility has the highest permeability and the lowest permselectivity

ODPA-DABP with the smallest free- volume and the smallest intrasegmental mobility has the lowest permeability and the lowest permselectivity

ODPA-DMMDA with the larger free-volume and smaller intrasegmental mobility has higher permeability and higher permselectivity.