Sulfonated poly(ether imide): A versatile route to prepare functionalized polymers by homogenous sulfonation

摘要

This work deals with the PEI/ULTHEM sulfonation using acetyl sulfate aiming to obtain chemically and thermally stable polymeric materials employed as membranes. The commercial PEI was chemically modified by homogenous sulfonation reaction, which was conducted with acetyl sulfate prepared by mixing acetic anhydride and sulfuric acid, using N-methyl-2-pyrrolidone (NMP) as polymer solvent. The sulfonated PEI (PEI-SO_3H) films with sulfonation range around 0.02-0.8% were obtained and characterized by Fourier transform infrared spectroscopy, ion exchange capacity, water sorption and glass transition temperature. The PEI-SO_3H films with different sulfonation level were more thermally stable (Tg = 200145℃) than commercial membranes, Nafion™ 117 (Tg= 110℃). Dense membrane was prepared with good mechanical properties and showed to be swollen by water. PEI-SO_3H films show that the increase of the sulfonation level led to higher values of water sorption and the IEC properties.