Effects of hydrolyzed PIM-1 in polyimide-based membranes on C2-C4 alcohols dehydration via pervaporation

- Exploration the potential of gas separation membranes for pervaporation applications.
- A simultaneously good flux and separation factor have been achieved by optimizing the blend ratio.
- Matimid/cPIM-1(80:20) has high flux >2 kg µm/m2 h and separation factor in 1-butanol dehydration.
- Matrimid/cPIM-1 film has the best compatibility and the most severe alcohol-induced swelling.

Polymers of intrinsic microporosity, specifically PIM-1, have attracted significant attention for gas separation due to its relatively high permeability and reasonably good selectivity. Although few studies evaluated the potential of PIM-1 in pervaporation, their dehydration performance was not impressive because of low selectivity. In this work, we aim to develop a simple but effective approach to enhance the selectivity of PIM-1 while preserving its high permeability for pervaporation dehydration through blending it with different polyimides. The miscibility characteristics of the newly developed membranes in terms of free energy of mixing are examined by molecular simulation while the degrees of swelling in solvents and the changes in interstitial space are characterized by sorption analyses and X-ray diffraction (XRD), respectively. By optimizing the blend ratio, a simultaneously good flux and separation factor have been achieved. For example, the Matrimid membrane containing 20 wt% hydrolyzed PIM-1 (hPIM-1) possesses a high flux of exceeding 47.8 g/m2h and a separation factor of more than 5000 for the dehydration of 1-butanol. This work may provide an inspiration of exploring the potential of gas separation membranes for pervaporation applications.

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