Synthesis and Characterization of Some Triphenylamine (TP A) Based Polyimides with Pendant N-Alkoxy Chains

Abstract

Polyimides are available in thermoset and thermoplastic forms, are frequently used in adhesives, coatings, laminates, and encapsulating materials. Their lower solubility, high glass transition temperature, and melting temperature which were attributed to the strong intermolecular interactions which limit their processing and fabrication. The goal of this research was to synthesize triphenylamine-based polyimides having flexible n-alkoxy pendant groups in their backbone. Both triphenylarnine unit and methylene spacer are packing disruptive thus preventing the formation of strong interaction between polymer chains. For this purpose, three diamine monomers having n-alkoxy groups of various chain lengths were synthesized with high purity and yield. The newly synthesized monomer diamines were polymerized using commercially available four dianhydride, 4,4'-(hexafluoroisopropylidine )dipthalic anhydride (6-FDA), 4,4'- oxydipthalic anhydride( 0 D P A), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), pyromellitic dianyhydride (PMDA), resulting in the formation of eight polyimide films. A two-step thermal imidization procedure was used to synthesize polyimides. The synthesized polyimides were analyzed using physical data, FTIR spectroscopy, NMR, XRD, UV-Vis spectroscopy, cyclic-voltarnmetry, and DSC techniques. The synthesized polyimide films have appreciable solubility in organic solvents such as NMP, m-Cresol, and DMAc facilitating their processing and fabrication. The optical and electrochemical properties of all the synthesized polyimide films were investigated. The high laying HOMO - (5.00-6.00) and low energy band gap (Eg values: 2.7-3.1) indicated that these polyimides can be employed in optoelectronics.