Chemically synthesized poly(o-methoxyaniline): influence of counterions on the structural and electrical properties

Abstract

Poly(o-methoxyanilines) (POMA) were chemically synthesized using different dopant acids to obtain the polymers POMA/HCl, POMA/HNO3, POMA/H2SO4 and POMA/H3PO4. The nature and size of the counterions influenced considerably on the structural, morphological, thermal and electrical properties of the as-synthesized polymers. X-ray Diffraction (XRD) patterns presented slightly peak displacements according to the dopant acid, influencing the lattice parameters specially along [010]. The polymers POMA/HCl, POMA/HNO3 and POMA/H2SO4 presented similar percentage of crystallinity (around 50 %), while the polymer POMA/H3PO4 was the less crystalline (around 40 %). Polymer morphology was dependent on the dopant acid, besides multimorphologies were observed in the polymers POMA/HCl, POMA/HNO3 and POMA/H3PO4. A great counterion influence from the doping acid was found in the electrical properties. The total variation obtained in DC conductivity was five orders of magnitude. The calculated values were 6.6 x 10-1 S/cm, 1.11 x 10-2 S/cm, 3.64 x 10-3 S/cm and 5.2 x 10-4 S/cm for POMA/HCl, POMA/HNO3, POMA/H2SO4 and POMA/H3PO4, respectively. The use of HCl as dopant potentiated the DC conductivity of the polymeric material.c