Penetrated COF Channels: Amino Environment and Suitable Size for CO 2 Preferential Adsorption and Transport in Mixed Matrix Membranes

Developing mixed matrix membranes (MMMs) is challenging because the interface between different matrices often forms undesirable structures. Herein, we demonstrate a method of creating suitable CO 2 -selective channels based on interface regulation that greatly enhances membrane separation performance. The poly(vinylamine), which also acts as a polymer matrix, was immobilized onto covalent organic frameworks (COFs) to obtain polymer–COF hybrid materials (COF p ). The COF p and polymer matrix are highly compatible because they have the same segment. The polymer matrix was induced to penetrate the oversized COF p, resulting in an amino-environmental pore wall and appropriately sized CO 2 -selective channels dispersed in MMMs. The MMMs exhibited satisfactory membrane performance for CO 2 /N 2, CO 2 /CH 4, and CO 2 /H 2 separation. A CO 2 transport model for preferential adsorption and transport is clearly presented for the first time. The membrane separation mechanism is also discussed. This work demonstrates potential applications for material, interface, and membrane investigations.