A comparative study on the properties of aromatic polyamides with methyl- or trifluoromethyl-substituted triphenylamine groups

Two triphenylamine-based diamine monomers, 4,4'-diamino-4 ''-methyltriphenylamine and 4,4'-diamino-4 ''-(trifluoromethyl)triphenylamine, were synthesized via the cesium fluoride-mediated double N-arylation reactions of p-toluidine and p-(trifluoromethyl)aniline, respectively, with p-fluoronitrobenzene, followed by palladium-catalyzed hydrazine reduction of the dinitro intermediates. New redox-active aromatic polyamides containing main-chain triphenylamine unit with methyl or trifluoromethyl (-CF3) group on the pendent phenyl ring were prepared by the phosphorylation polycondensation reactions of the synthesized diamine monomers with commercially available aromatic dicarboxylic acids. The polyamides were readily soluble in polar organic solvents and could afford flexible and strong films via solution casting. Cyclic voltammograms of the polyamide films cast onto the indium tin oxide (ITO)-coated glass substrate revealed reversible electrochemical oxidation processes accompanied with color change from pale yellow to dark golden or green. Comparative studies of the methyl and -CF3 substituents on the properties of the polyamides, such as solubility, thermal, electrochemical and electrochromic properties, are investigated. (C) 2016 Elsevier B.V. All rights reserved.