GAS-TRANSPORT PROPERTIES OF BIPHENOL POLYSULFONES

Gas sorption and transport properties at 35-degrees-C are reported for the polysulfone based on 4,4'-biphenol (BIPSF) and corresponding polysulfones with methyl ring substitutions, tetramethylbiphenol polysulfone (TMBIPSF) and hexamethylbiphenol polysulfone (HMBIPSF). Comparisons are made to bisphenol A polysulfone (PSF) and tetramethylbisphenol A polysulfone (TMPSF). BIPSF and PSF have very similar transport characteristics. This is attributed to the similar packing behavior of these polymers. Tetramethyl substitution on the biphenyl rings increases permeability, while hexamethyl substitution does not lead to a comparable further increase but does enhance selectivity characteristics for certain gas pairs. Permeability values are discussed in terms of chain packing, fractional free volume, and sub-T(g) relaxation behavior.