Chemical oxidative polymerization of m-phenylenediamine and its derivatives using aluminium triflate as a co-catalyst

Aromatic diamine monomers, including m-phenylenediamine (mPD), 2-methyl-m-phenylenediamine (2Me-mPD), 4-methyl-m-phenylenediamine (4Me-mPD) and trimethyl-m-phenylenediamine (tMe-mPD), 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 polymerization conditions. The polymerization yield was improved when Al(OTf)3 was introduced to the polymerization reaction for most polymers. The poly(2-methyl-m-phenylenediamine) (P(2Me-mPD)), poly(4-methyl-m-phenylenediamine) (P(4Me-mPD)) and poly(trimethyl-m-phenylenediamine) (P(tMe-mPD)) polymers exhibited better solubility than poly(m-phenylenediamine) (P(mPD)) polymers in most common solvents. The homopolymers obtained were characterized by FT-IR, 1H and 13C NMR, WAXD and TGA. The results showed that the yield, solubility and structure of the polymers are significantly dependent on the polymerization conditions. TGA measurements indicated that the polymers have good thermal stability and decompose above 400 °C in nitrogen.