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

Area of Science:

• Materials Science
• Polymer Chemistry
• Separation Science

Background:

• Development of advanced materials for efficient gas separation is crucial.
• Polyimides are promising candidates for membrane-based gas separations.
• Incorporating flexible segments can modify polymer properties for tailored performance.

Purpose of the Study:

• To synthesize and characterize novel CO2-selective polyimides.
• To investigate the structure-property relationships of copolymers with varying PDMS content.
• To evaluate the CO2 separation performance of the developed membranes.

Main Methods:

• Copolymerization of crown ether diamine and PDMS-diamine with 6FDA via polycondensation.
• Comprehensive characterization using NMR, FTIR, TGA, DSC, XRD, and GPC.
• Analysis of membrane morphology and gas separation performance.

Main Results:

• Successful synthesis of CO2-selective polyimides (CE-PDMS-PI-x).
• Low PDMS content (5 wt%) significantly improved CO2 separation performance due to enhanced morphology.
• Higher PDMS loading (≥20%) provided flexible diffusion paths, increasing permeability without compromising selectivity.

Conclusions:

• A strong structure-property relationship was established for the CE-PDMS-PI-x copolymers.
• PDMS incorporation offers a tunable approach to optimize membrane performance for CO2 separation.
• These polyimides demonstrate potential for advanced gas separation applications.