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

• Two triphenylamine-based diamine monomers with methyl or trifluoromethyl substituent have been synthesized.
• New redox-active and electrochromic polyamides with either 4-methyltriphenylamine or 4-(trifluoromethyl)triphenylamine units were prepared.
• The polyamides showed green or dark golden coloring upon oxidation.
• Effects of the CF3 substituent on the properties of the polyamides have been investigated.

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.

A new fluorine-containing, triphenylamine-based diamine monomer, 4,4′-diamino-4″-(trifluoromethyl)triphenylamine, was synthesized and led to a series of electroactive aromatic polyamides. The electrochemical and electrochromic properties of the polyamides were investigated and compared with the those of analogous polyamides based on 4,4′-diamino-4″-methyltriphenylamine.Figure optionsDownload as PowerPoint slide