In-situ growth of MOF nanofillers in Pebax matrix for excellent CO2 permeability improvement

Abstract

The trade-off between high filler loadings and membrane performance remains a critical challenge in mixed matrix membranes (MMMs), where the pursuit of high gas permeability via increased filler loading often leads to nanoparticle agglomeration and interfacial defects, compromising selectivity and mechanical integrity. In this work, a facile in-situ growth strategy was developed to incorporate high-loading ZIF-8 nanofillers uniformly into Pebax® 2533 matrix. The obtained mixed matrix membranes achieved an ultrahigh ZIF-8 loading of ~27.7 wt% with excellent dispersion and strong interfacial adhesion, effectively mitigating agglomeration and interfacial defects. The optimal membrane exhibited a remarkable CO2 permeability of 1116 Barrer, representing an approximately 250% enhancement over the neat Pebax membrane, while maintaining comparable CO2/N2 selectivity. Comprehensive characterization and mechanistic studies revealed that the performance enhancement was primarily governed by significantly improved solubility selectivity, attributed to the strong CO2 adsorption affinity of the in-situ grown ZIF-8 framework. Moreover, the well-dispersed MOF nanoparticles restricted polymer chain mobility, endowing the MMM with improved mechanical strength and long-term operational stability. This work provided a universal strategy for achieving high-loading, well-compatible MOF incorporation in rubbery polymers, also demonstrated a promising pathway toward scalable fabrication of efficient and stable membranes for practical CO2 capture applications.