Anodic polymerization of 1-amino-2-methyl-9,10-anthraquinone in mixed solvent

Poly(1-amino-2-methyl-9,10-anthraquinone) (PAMAQ) was synthesized at glassy carbon (GC) electrode using 1-amino-2-methyl-9,10-anthraquinone (AMAQ) dissolved in a binary (1:1) solvent mixture containing acetonitrile (ACN) and 5 M H₂SO₄ employing a continuous cyclic voltammetry or controlled potential electrolysis (CPE) techniques. Electrochemical responses of the prepared polymer films were studied in 1 M H₂SO₄ aqueous solution. A number of factors affecting the film formation such as potential limits, scan rates, number of cycles, monomer concentration, nature of electrolytes and polymerization techniques were examined in details. The effect of scan rates and electrolyte composition on the electroactivity of the resulting polymeric films were tested also. The optimum conditions for the film formation were sweeping the electrode potential between -0.7 V and +1.8 V at a scan rate of 50 mV/s for 25 cycles using 1 mM of the monomer (AMAQ). The prepared modified electrode was found to be highly electroactive and stable in 1 M H₂SO₄ supporting electrolyte but the polymerization process diminished completely when 0.1 M LiClO₄/ACN or 0.1 M Bu ₄NClO₄/ACN was used as a result of polymer instability and film solubilization. The solubility of the polymeric film has been confirmed by following up the electropolymerization of AMAQ applying UV-Vis technique. Poly(1-amino-9,10-anthraquinone) (PAAQ) was also prepared using the same binary solvent mixture. The redox behaviour and the stability of PAAQ were found to be different in the negative domain compared with PAMAQ. The effect of the presence of the methyl group in the structure of the aminoquinone was discussed.