Sorption, transport, and history effects in phenolphthalein-based polysulfone

Abstract

Sorption and permeation characteristics of CO₂ and CH₄ in phenolphthalein-based polysulfone (PSF-PPHA) were investigated. The incorporation of the bulky phthalide ring at the bridge carbon atom of bisphenol A results in an increase in T_g by 100°C compared to that of bisphenol-A-based polysulfone (PSF). The increase in T_g leads to enchanced sorption characteristics for CO₂ and CH₄ in the Langmuir mode. The mobility of CO₂ in the Langmuir mode has also been found to be higher than that in the case of PSF. Although the intersegmental chain spacing of PSF-PPHA is practically the same as that of PSF, the former polymer exhibits higher permeability for CO₂ without a significant loss in selectivity with respect to CH₄. The permeation study using a CO₂:CH₄ (55:45 mole ratio) mixture indicates that the selectivity of PSF-PPHA is less susecptible to plastization, at least in the pressure range 3-40 atm at 35.0°C.