Synthesis of poly(1-aminonaphthalene) and poly(1-aminoanthracene) by chemical oxidative polymerization and characterization of the polymers

Abstract

Poly(1-aminonaphthalene) and poly(1-aminoanthracene) have been synthesized in high yields (90--96%) by chemical oxidative polymerization of 1-aminonaphthalene and 1-aminoanthracene using H{sub 2}O{sub 2} in the presence of Fe catalyst. The oxidative polymerization of 1-aminonaphthalene and 1-aminoanthracene proceeds via successive coupling that gives the polymer structure similar to polyaniline. The polymers are brown powders and soluble in dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), H{sub 2}SO{sub 4}, and HCOOH. The obtained poly(1-aminonaphthalene) and poly(1-aminoanthracene) show electrical conductivities of 1.7 {times} 10{sup {minus}6} and 1.6 {times} 10{sup {minus}4} S cm{sup {minus}1}, respectively, which increase to 3.8 {times} 10{sup {minus}4}-1.5 {times} 10{sup {minus}3} S cm{sup {minus}1} on doping with HCl or I{sub 2}. Light scattering measurements of the polymers in NMP shows a large degree of depolarization ({rho}{sub v} = 0.33), indicating that the polymers have a linear and stiff structure. The number-average molecular weights (M{sub n}) of poly(1-aminonaphthalene) and poly(1-aminoanthracene) obtained are determined as 4,300 and 4,500, respectively, with narrow molecular weight distribution by gel permeation chromatography (vs polystyrene). The weight-average molecular weight (M{sub b}) of poly(1-aminoanthracene) determined by the light scattering method is 7,000. {sup 1}H NMR spectra of PNA and PAA in DMSO-d{sub 6} give rise to the absorption of themore » NH hydrogen in the region of {delta} 5--6 ppm, and the NH hydrogen of PNA is exchangeable with the water hydrogen contained in DMSO-d{sub 6} on the NMR time scale with an activation energy of 27 kJ mol{sup {minus}1}. PNA and PAA do not show a distinct absorption peak in the visible region.« less