기체 분리용 폴리술폰-폴리에틸렌옥사이드 공중합체

Abstract

Polysulfone-poly(ethylene oxide) (PSF-PEO) multiblock copolymer membranes with rigid and flexible chain were investigated gas separation properties including gas solubility, diffusivity and permeability. In this study random copolymers were synthesized using a polycondensation reaction via nucleophilic substitution. The PEO containing PSF multiblock copolymer membranes were prepared by varying PEO content from 5 mol% (9 wt.%) to 20 mol% (31 wt.%) in a glassy PSF matrix to see the effects of PEO segments on the change of physical properties (e.g., density and glass transition temperature), water affinity (e.g., contact angle and water uptake), thermal properties (e.g., thermal degradation temperature), mechanical properties (e.g., elongation at break and tensile strength) as well as gas transport properties. The gas diffusivity, solubility and permeability of light gases (e.g., He, H2, O2, N2, CO2 and CH4) in these copolymer membranes were measured as a function of PEO content in PSF, and discussed in relation to the changes in physical and mechanical properties. We expected that the incorporation of amorphous, flexible PEO segments in a stiff, glassy polymer such as PSF could yield to increase in gas permeabilities, particularly CO2 permeability because PEO segments with polar ether oxygen units is known to have good affinity with CO2 molecules, thereby leading to high level of CO2 sorption. However, all gas permeabilities, including CO2 permeability, were unexpectedly reduced with the increase of PEO content and the permselectivities of gas pairs of interest (e.g., CO2/H2, CO2/N2 and CO2/CH4) were not improved as we expected. In this paper, we will discuss in detail from the standpoint of the structure-gas property relations in PSF-PEO segmented multiblock copolymer membranes regarding these phenomena.