High Gas Permeability in Aged Superglassy Membranes with Nanosized UiO‐66−NH<sub>2</sub>/cPIM‐1 Network Fillers
Boya Qiu, Ming Yu, José Miguel Luque‐Alled, Shengzhe Ding, Andrew B. Foster, Peter M. Budd, Xiaolei Fan, Patricia Gorgojo
Abstract
Abstract Superglassy membranes synthesised by polymers of intrinsic microporosity (PIMs) suffer from physical aging and show poor gas permeance over time, especially thin membranes, due to the fast rearrangement of nonequilibrium polymer chains. Herein, we constructed a novel PIM‐1 thin film nanocomposite membrane (TFN) using nanosized UiO‐66−NH 2 (≈10 nm)/carboxylated PIM‐1 (cPIM‐1) as the composite filler. Unlike conventional fillers, which interact with the polymer only via the surface, the UiO‐66−NH 2 /cPIM‐1 forms a stable three‐dimensional (3D) network intertwining with the polymer chains, being very effective to impede chain relaxation, and thus physical aging. Nanosizing of UiO‐66−NH 2 was achieved by regulating the nucleation kinetics using carbon quantum dots (CQD) during the synthesis. This led to increased surface area, and hence more functional groups to bond with cPIM‐1 (via hydrogen bonding between −NH 2 and −COOH groups), which also improved interfacial compatibility between the 3D network and polymer chains avoiding defect formation. As a result, the novel TFN showed significantly improved performance in gas separation along with reduced aging (i.e. ≈6 % loss in CO 2 permeability over 63 days); the aged membranes had a CO 2 permeance of 2504 GPU and ideal selectivity values of 37.2 and 23.8 for CO 2 /N 2 and CO 2 /CH 4 , respectively.