Synthesis and Characterization of Fluorene-Based Polybenzimidazole Copolymer for Gas Separation

Abstract

The purpose of this study is to develop new cardo-polybenzimidazole (CPBI) copolymers containing cardo fluorene, with improved gas permeability, specifically oxygen permeability. The characteristics of these copolymers are investigated by Fourier transform infrared spectroscopy, nuclear magnetic resonance, H-1 and C-13), thermo-gravimetric analysis, and wide-angle X-ray diffraction. These membranes fabricated from copolymers have relatively high oxygen diffusion coefficients, determined using gas permeation. In particular, the CPBI-co91 (synthesized by using the monomers ratio containing dibenzoic acid=9 : 1) membrane have oxygen permeability coefficient (P-O2) of 10.69 Barrer, theoretical selectivity of 5.4 for oxygen to nitrogen, and O-2 diffusion coefficient of 9.64 x 10(-8) cm(2)/s.