Abstract
Novel multi-stimuli responsive cotton fibers were developed via spray-coating with an acylhydrazone-based polyviologen (AHPV). Polyviologen was prepared by supramolecular condensation polymerization of bipyridinium dialdehyde with a hydroxyl-substituted aryldihydrazide in an acidified aqueous medium. Transparent AHPV/resin nanocomposite film was deposited onto the surface of cotton fabric by well-dispersion of AHPV as a chromogenic substance in a resin binding agent. Increasing the temperature of the AHPV-coated cotton fabric from room temperature to 85 °C reversibly triggered a change in color from pale yellow (437 nm) to green (607 nm), respectively. The transparent layer immobilized onto the white cotton surface transformed into green under ultraviolet source as demonstrated by CIE Lab parameters. The photochromic impacts were explored at various AHPV. In addition, the AHPV-coated cotton immediately displayed a vapochromic activity upon exposure to NH3(g), and then recovered to pale yellow after removing the ammonia source away. The current AHPV-coated cotton fabric displayed a limit of detection (LOD) to NH3(aq) in the range of 50–150 ppm. The spray-coated cotton fabrics demonstrated a reversible photochromism, thermochromism and vapochromism with high stability. The produced AHPV nanoparticles were also studied by transmission electron microscopy (TEM), demonstrating particle diameter of 74–92 nm. The mechanical and morphological properties of the spray-coated cotton fabrics were also explored. The surface morphology of AHPV-finished samples was examined by Fourier-transform infrared (FTIR) and scanning electron microscopy (SEM). No considerable defects were observed in permeability to air and bending length of AHPV-finished samples. Additionally, high colorfastness was monitored for the AHPV-finished cotton substrates. The cytotoxic activity of the AHPV-finished cotton was also examined. Mechanistic study accounting for the multichromic activity of acylhydrazone-based polyviologen is explored.