Enhancing polymer compatibility and dispersibility of nanofiller via Zn2+-PVAm synergistically modified UIO-66-(COOH)2 for preparing high-performance CO2-separation MMMs

Mixed matrix membranes (MMMs) have demonstrated remarkable advantages in gas separation applications through the synergistic integration of polymeric matrices and nanostructured reinforcements. While these advanced composite thin-film materials exhibit substantial potential for CO 2 separation, their industrial-scale implementation confronts threefold challenges: elevated manufacturing costs, interfacial compatibility optimization between nanofillers and polymer matrices, and performance enhancement requirements for achieving superior separation efficiency. In this study, the green and economical nanofiller UIO-66-(COOH) 2 (denoted as UC) was strategically selected. A novel strategy involving synergistic modification using Zn 2+ and polyvinylamine (PVAm) was developed to address the critical challenge of severe particle agglomeration and sedimentation. This phenomenon, caused by intense electrostatic interactions between the strongly negatively charged UC and the cationic polymer PVAm during surface modification, was effectively mitigated through the proposed cooperative modification mechanism, resulting in the successful synthesis of P@UC-Zn exhibiting exceptional dispersibility and enhanced compatibility with the polymeric matrix. The fabricated P@UC-Zn-PVAm/mPSf MMMs containing 35 wt% filler exhibited remarkable CO 2 permeance (3250 GPU) and selectivity (166) under feed gas conditions (CO 2 /N 2  = 15/85 vol%, feed pressure: 2 bar). Furthermore, the optimized MMMs demonstrated robust operational stability in simulated flue gas tests and showed potential for applications in carbon dioxide-methane and carbon dioxide-hydrogen separations.