Synthesis and characterization of green membranes polyimide/titania bionanocomposites containing amino acid and benzimidazole moieties for gas transport properties

Abstract

In the presented study, the synthesis and full characterization of four different new diamine and polyimides derived from amino acids, including isoleucine (Ile), valine (Val), methionine (Met), phenylalanine (Phe) and benzimidazole fractions in the structure of pendant group is presented. The polymerization reactions of these monomers provided a series of new optically active polyimides (PIs) with inherent viscosities in the range of 0.68–0.98 dL g−1. The obtained polymers were characterized by Fourier‐transform infrared spectroscopy, specific rotation measurements, and the representative of them by proton nuclear magnetic resonance, gel permeation chromatography and elemental analysis techniques. The new diamine monomer containing L‐isoleucine is employed as a key monomer for the sol–gel fabrication of a series of PI/titania nanohybrid films with various titania percentages. The special design of diamine monomer containing bulky pendant group increased the flexibility of resulted PIs. On the other hand, the ability to construct strong organic/inorganic H‐bond lattice has led to the effective surrounding of titania by PI grounds and thus the well‐dispersed quite spherical NPs were created via a sol–gel procedure. The dispersion of titania in PI films was confirmed by the transmission electron microscope (TEM) analysis showing the well‐dispersed nanosized titania NPs. The thermogravimetric analysis data showed an improvement of thermal stability of novel bionanocomposite films as compared to the pure PI. Gas permeation measurement showed that PI embedded with different amount of titania exhibited different separation performances. POLYM. ENG. SCI., 58:1666–1677, 2018. © 2017 Society of Plastics Engineers