CO₂ selective separation of Pebax-based mixed matrix membranes (MMMs) accelerated by silica nanoparticle organic hybrid materials (NOHMs)

Liquid-like nanoparticle organic hybrid materials (NOHMs) hold great promise in CO₂ capture due to tailored nanostructures and functionalities. Herein, we demonstrate a facile and generic method to enhance CO₂ selective separation of Pebax-based MMMs by NOHMs. NOHMs with core/corona/canopy structure based on silica with different particle size (120 nm, 220 nm and 380 nm) were prepared, respectively. The basic physicochemical properties of NOHMs and MMMs were examined. Excellent interface compatibility is obtained due to the peculiar property of liquid-like NOHMs in resolving nanoparticles agglomeration. More importantly, CO₂-philic moieties (EO segments) in canopy (polyetheramine M2070) endow MMMs with a superior CO₂ selective separation. The effect of NOHMs content on mixed gases permeation were systemically investigated. Remarkably, the optimum CO₂ permeability reached 246.7 Barrer and a satisfied CO₂/N₂ selectivity of 66.4 for membrane (P-NOHMs-120-(15)) was obtained, which were increased by 267.1% and 76.1% compared with pristine Pebax membrane, respectively. Moreover, Grand Canonical Monte Carlo (GCMC) molecular simulation was used to investigate how NOHMs improve CO₂ selective separation by analyzing interaction parameters (interaction energy, density field distribution and isosteric heat). Finally, the enhanced CO₂ selective separation sites were determined. The CO₂ selective separation accelerated by NOHMs proposed in present work provides ingenious inspiration for the development of novel fillers in MMMs due to the tailored nanostructures of NOHMs.