Development of CO2-Selective Polyimide-Based Gas Separation Membranes Using Crown Ether and Polydimethylsiloxane

Abstract

A series of CO2-selective polyimides (CE-PDMS-PI-x) was synthesized by copolymerizing crown ether diamine (trans-diamino-DB18C6) and PDMS-diamine with 4,4′-(hexafluoroisopropylidene) di-phthalic anhydride (6FDA) through the polycondensation reaction. The structural characteristics of the copolymers and corresponding membranes were characterized by nuclear magnetic resonance (NMR), infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and gel permeation chromatography (GPC). The effect of PDMS loading on the CE-PDMS-PI-x copolymers was further analyzed and a very good structure–property relationship was found. A well-distributed soft PDMS unit played a key role in the membrane’s morphology, in which improved CO2-separation performance was observed at a low PDMS content (5 wt %). In contrast, the fine-grained phase separation adversely affected the separation behavior at a certain level of PDMS loading, and the PDMS was found to provide a flexible gas-diffusion path, affecting only the permeability without changing the selective gas-separation performance for the copolymers with a PDMS content of 20% or above.

Novel cardo‐type heat‐resistant polyimides bearing 9H‐xanthene and polymer‐based nanocomposite consisting of NH2‐terminated TiO2: Synthetic strategies, extraction of methylene blue dye, and biological activities

“…22,23 Abundant efforts have been made to improve processing virtues of PIs, especially, by enhancing their fusibility and solubility, while keeping thermal constancy. Incorporation of ring-shaped structures, 24 nonplanar structures, 25 bulky side groups, 26,27 flexibilitie s linkages, 28 cardo groups, 29,30 and heterocyclic ring [31][32][33] are among modification methods used for improving properties of PIs.…”

Modified Graphene Oxide-Incorporated Thin-Film Composite Hollow Fiber Membranes through Interface Polymerization on Hydrophilic Substrate for CO2 Separation

“…Carbon capture and storage (CCS) is a technology that can capture, purify, compress, and transport CO 2 and store it safely under the Earth’s surface [ 4 , 5 , 6 , 7 ]. There are several types of CO 2 separation or capture approaches depending on various parameters, such as concentration of CO 2 in the gas stream, the pressure of the gas stream, and the fuel type (solid or gas) for selecting the capture system [ 8 , 9 ].…”