Fluorine-containing polyimides have been widely used as adhesives, electronic components, and gas separation membranes because of their good thermal stability, mechanical strength, low dielectric constant, and high gas permeability compared with other general polyimides. Until now, gas separation membranes have been modified to improve gas permeability and selectivity. Although the crosslinking of polymer segments is one of the effective methods for improving gas separation performance, the excessive crosslinking density of polymer membranes significantly reduces gas permeability because of membrane densification. Previously, we reported that the synthesis and gas permeation properties of ultraviolet (UV) -cured fluorine-containing telechelic polyimide membranes end-capped with acryloyl groups. We obtained self-standing membranes from telechelic polyimides by casting method under UV irradiation. In this study, the physical and gas separation properties of UV-cured membranes with crosslinker were investigated. The membrane formation property using UV irradiation was improved by the addition of crosslinker. The membrane density and the mean distance between the polyimide segments (i.e. d-spacing) of the UV-cured membranes with the crosslinker were almost the same, but with a high gel content, which suggests that crosslinker promotes crosslink reaction at the polymer chain ends and prevents the membrane densification. Furthermore, the gas permeability of the UV-cured membranes with crosslinker was higher than that of the membrane without the crosslinker. This is because the new cross-linking structure formed at the polymer chain ends with the crosslinker after UV irradiation and prevents the membrane densification. Therefore, the use of crosslinker in the telechelic polyimide membranes promotes the cross-linking reaction and increases the gas selectivity without significantly decreasing the gas permeability due to the suppression of the membrane densification.

Preparation and gas separation properties of UV-cured fluorine-containing telechelic polyimide membranes with crosslinker

248th National Meeting (2014)

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