Microporous polyimine membranes for efficient separation of liquid hydrocarbon mixtures.

Interfacial polymerization has been an industrial standard for preparing desalination membranes. Extending the same concept to molecular separation of organic solvents would be a key enabler for the decarbonization of the chemical and petrochemical industries through energy-efficient crude or biocrude oil fractionation. Here, we report a molecular engineering approach based on acid-catalyzed interfacial polymerization for efficient hydrocarbon separation. The design strategies include (i) changing the linkage from amide to imine and (ii) subsequent introduction of shape-persistent units such as triptycene and spirobifluorene. The prepared polyimine membranes exhibit ultrahigh microporosity and enhanced swelling and plasticization resistance compared with conventional polyamide counterparts. These membranes, which feature fast and selective transport of hydrocarbons, including multicomponent and industrially relevant mixtures, outperform commercial and state-of-the-art benchmark membranes.