Intrinsically microporous oligomers as organic porogens for mixed-matrix membranes

Intrinsically microporous oligomers (or oligomers of intrinsic microporosity, OIM) for use as organic poro-gens were first synthesized and subsequently incorporated into polysulfone (PSU) matrices to produce mixed-matrix membranes (MMMs) for gas separation. Their molecular weight was controlled to be about Mn=2,800 (n~5–6), and their end groups were regulated to be either -OH (OH-OIM) or -F (F-OIM) for improvement in the compatibility between OIM and PSU. The intrinsic pores of OIM greatly increase the gas permeability of PSU with only a small loss of gas selectivity. For instance, 20/80 wt% OH-OIM/PSU MMMs yield up to three- to four-fold higher permeability of CO2 and He compared to neat PSU, mostly associated with the intrinsic pores of OIM and its high compatibility with PSU. Additionally, very little reduction in separation performance was observed over 100 days. This suggests OIM as a promising organic porogen of MMMs for improving gas separation performance.