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

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.