Fully Aromatic Fluorinated Polyamide Nanofilms with Molecular Gating for Ultrafast Crude Oil Fractionation

Abstract Crude oil is the “black gold” of the world and its fractionation by thermal distillation is a highly energy‐consuming process. Polymer membranes are manifesting the potential in revolutionizing crude oil fractionation for developing energy‐efficient, low‐footprint petrochemical engineering. Nevertheless, conventional polymer membranes suffer from inferior fractionation performance with unsatisfied permeance and selectivity owing to their polar channel chemistry as well as low‐connective and vulnerable channel architecture. We report a kind of robust, fully aromatic fluorinated polyamide (FAFPA) nanofilm that features a switchable molecular gating‐on/gating‐off state to activate and reconstruct sub‐nanochannels for the permselectivity of hydrocarbon liquids, enabling ultrafast and stable crude oil fractionation. We demonstrate the gating‐on state is launched by the interplay of FAFPA networks and polar‐matched trigger molecules bearing α‐H such as alcohols and ketones, redefining the sub‐nanochannel chemistry and improving the spatial connectivity of sub‐nanochannels to accelerate the selective transport of hydrocarbons. The gating‐on FAFPA nanofilms show a record‐high separation factor of 33 for 1,3,5‐triisopropylbenzene with a molecular weight of 204 Da as well as a profound n ‐hexane permeance, 24‐fold higher than that of the gating‐off state. Moreover, these gating‐on FAFPA nanofilms can stably handle typical black crude oil at an elevated temperature of 80 °C for garnering a 32‐fold increased permeance while sustaining nearly constant selectivity toward hydrocarbons.