Mechanochemical processing of interface-integrated mixed-matrix membranes for efficient gas separation

Abstract

Mixed-matrix membranes (MMMs), which are hybrids of nanoporous fillers and polymers, show great potential for energy-saving separation and offer ideal platforms to address the permeability-selectivity trade-off, scaling-up, and aging issues associated with polymer membranes and pure nanoporous membranes. However, achieving tight interphase integration to design high-performance MMMs remains extremely challenging. In this study, mechanochemistry was employed to construct interface-integrated MMMs based on metal–organic frameworks and polymers of intrinsic microporosity-1 for efficient gas separation. The characterization and molecular dynamics simulation demonstrated that mechanochemical processing via the facile, scalable, and versatile ball milling method could disrupt the crystalline periodicity on the filler surface to form disordered interfaces and promote polymer-in-filler insertion and filler-matrix integration, thereby substantially enhancing the filler dispersity, interfacial compatibility, separation performance, and antiaging property of MMMs. After natural aging for 220 days and humidity/temperature-swing operations, the CO₂ and CH₄ permeability and CO₂/N₂ and CH₄/N₂ selectivity of the interface-integrated MMMs still reached 18 400 and 1500 Barrer and 32.1 and 4.0, respectively, easily surpassing the least upper bound performance. It can be envisaged that the concept reported herein provides an alternative route to achieve the desired properties and maximize the separation performance of MMMs.