GO as gutter layer in superglassy thin film composite membranes for enhanced gas separation

Polymers with intrinsic microporosity (PIM) have gathered considerable attention over the last two decades for fabricating high-performance membranes for CO₂ separation, owing to their highly permeable and porous structures. Particularly, thin film composite (TFC) membranes with thin active layers (<5 μm) deposited onto more porous substrates are suitable for practical applications as they offer a combination of high permeance and mechanical strength. However, penetration of the active layer into the pores of the substrate leads to additional mass transfer resistance and creates defects and voids, thereby reducing the membrane's permeance and selectivity. Herein, we introduced graphene oxide (GO) as a gutter layer in TFCs made with PIM-1. GO flakes were deposited to cover the substrates partially, thereby reducing polymer penetration while maintaining good structural integrity of the TFCs. We successfully fabricated a series of PIM-1 TFCs by kiss coating, with the thinnest active layer at ∼179 nm. These TFCs exhibited an ideal selectivity for CO₂/N₂ of 44.4, and the CO₂ permeance was increased by up to 104 % under optimised conditions. The strategy is generic as well which was validated using carboxylated PIM-1 (cPIM-1).