Comparative study and dyeing performance of as-synthesized azo heterocyclic monomeric, polymeric, and commercial disperse dyes

In this study poly (4-nitrophenylazo-3-aminopyridine - formaldehyde) (PNAAP-F) and poly (4-nitroarylazo-3-chloro-6-hydroxypyridine - formaldehyde) (NAACHP-F) were synthesized via diazotization, coupling and polycondensation reactions. The structural properties of the as-synthesized dyes were acquired using Fourier-transform infrared spectroscopy (FTIR) and UV-visible absorption maxima and their color, yield, melting point, solubility, and viscosity were determined via standard methods. UV-visible and FTIR results show successful formation of the polymeric dyes due to shift of wavelength of maximum absorption (λmax) (440-490 nm, 480-540 nm) and new absorption peak at around (2780-2995 cm-1) for methylene bridge respectively. The dyes were found to be of good yield (monomeric: 73.3%-87.2 %, polymeric: 53.8%-76.6 %), low melting point (monomeric: 112.6-121.2, and 136.0-137.0 °C, while polymeric: 134.0-144.5, and 149.4-154.7 °C), soluble in some solvents. The dyeing activity was carried out and assessed on nylon and polyester fabrics using the standard methods. The dyeing process was carried out via high temperature and carrier dyeing methods. The dyeing properties of the synthesized dyes were compared with those of commercial disperse dyes (terasil brilliant violet and terasil scarlet, brown). The dyeings of nylon and polyester had a very attractive hue and the color ranges from yellow and deep yellow shades with very good to excellent fastness to light, washing, hot pressing, and rubbing.