Using aluminium triflate as a co‐catalyst for the polymerization of o ‐phenylenediamine and its derivatives

Aromatic diamine monomers, including o ‐phenylenediamine ( o PD ), 4‐methyl‐ o ‐phenylenediamine ( 4Me ‐ o PD), 4,5‐dimethyl‐ o ‐phenylenediamine (dMe‐ o PD) and 4‐( tert ‐butyl)‐ o ‐phenylenediamine (tBu‐ o PD), were polymerized by chemical oxidation using ammonium persulfate as an oxidant. Aluminium triflate (Al(OTf) 3 ) was also used for the first time as a co‐catalyst under various reaction conditions for the polymerization of o PD derivatives. The polymerization yield was improved when Al(OTf) 3 was introduced to the polymerization reaction for most polymers. The solubility of poly(4‐methyl‐ o ‐phenylenediamine) (P(4Me‐ o PD)), poly(4,5‐dimethyl‐ o ‐phenylenediamine) (P(dMe‐ o PD)) and poly(4‐( tert ‐butyl)‐ o ‐phenylenediamine) (P(tBu‐ o PD)) polymers was improved compared with the poly( o ‐phenylenediamine) (P( o PD)) polymers in most common solvents. The homopolymers obtained were characterized by Fourier transform IR spectroscopy, UV−visible spectroscopy, 1 H and 13 C NMR, wide‐angle X‐ray diffraction, DSC and TGA. The results showed that the yield, solubility and structure of the polymers are significantly dependent on the polymerization conditions. DSC measurements indicated that the polymers exhibited melting and crystallization transitions. The polymers also showed good thermal stability and decompose above 400 °C in nitrogen. © 2013 Society of Chemical Industry