Highly carboxylic acid functionalized PIM‐1 by hydrothermal method: Mechanistic study of gas separation properties

Abstract

Abstract This paper is dedicated to improve the conversion efficiency of carboxylation for polymers of intrinsic microporous (PIM‐1). According to stable thermal properties of PIM‐1, a hydrothermal method is used for the first time to achieve the carboxylation conversion of PIM‐1 (C‐PIM), achieving a conversion rate of more than 90% at a reaction time of 10 hours, which is nearly five times more efficient than the most efficient conversion process currently available, preserving the film‐forming properties. The completion of the carboxylation conversion is verified using 1H‐NMR and 13C‐NMR, FT‐IR, and organic elemental analysis. It is found that the change in molecular weight affected the film‐forming properties of the membrane material, and the hydrophobicity of the C‐PIM membrane did not decrease compared with C‐PIM membrane reported in previous studies. The effect of C‐PIM on the selectivity of CO2 gas is explained from the microscopic to the macroscopic level by using physical characterization such as molecular structure analysis, XRD, cross‐linkage calculation, pore size and volume distribution, and fractional free volume (FFV) calculation. It verifies that the efficiency of CO2 adsorption and diffusion selectivity for PIM‐1 membranes has been improved by carboxylation, preserving excellent separation, and capture capacity of CO2.

Keywords

• carboxylation
• CO2
• PIM‐1
• selectivity