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

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 1 H-NMR and 13 C-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 CO 2 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 CO 2 adsorption and diffusion selectivity for PIM-1 membranes has been improved by carboxylation, preserving excellent separation, and capture capacity of CO 2 .