Some quantitative studies of light fading of adsorbed dyes. Part 1.—Changes of light absorption of non-ionic dyes on fading, and their relation to the fading mechanism

Abstract

Measurements have been made of the ratio of extinction of the short-wave (y) and the long-wave ( x ) band in the visible region of spectra of four non-ionic (disperse) dyes sorbed in films of cellulose acetates, nylon, and polyester. The changes in the ratio with dye concentration and also with fading on exposure to light at given concentrations have been measured. The results are consistent with the presence of dye particles in a range of small sizes ; association of dye appears to occur during the dyeing process. The smaller sizes, probably molecularly disperse dye, predominate, especially in polyester, and these fade the most rapidly. The nature of the change in ratio with time of exposure suggests that dye molecules become more resistant to photochemical breakdown when associated together.

Dye chemistry with time-dependent density functional theory

“…81 Whilst such an approach allows a rapid estimation of the position of the absorption band of unknown anthraquinone, it cannot be considered as completely satisfying, as it gives no information on the experimental band shapes, and several hydroxy-and amino-anthraquinones are known to present multiple absorption peaks in the visible domain. 125,241,242 These multiple maxima have been associated with several effects, including aggregation, 243 tautomeric equilibrium [244][245][246] and vibrational couplings. 247 The actual origin has been fully resolved with TD-DFT for 1,4-NH 2 -9,10-anthraquinone (see representation in Fig.…”

TD-DFT Vibronic Couplings in Anthraquinones: From Basis Set and Functional Benchmarks to Applications for Industrial Dyes

“…However, if two or more hydrogen-bond donors (typically alcohols or amines) are grafted in positions 1, 4, 5, or 8, strong interactions with the carbonyl groups play a key role and modify the properties of both the ground and the excited states. Consequently, the visible band of these AQ derivatives often features a characteristic multipeak structure. ,,,, The origin of multiple absorption maxima in quinoidic dyes is not necessarily unique, and proposals to explain this effect include aggregation, tautomeric equilibrium, − and vibrational effects. , As we will demonstrate in this contribution, the latter explanation is by far the most appropriate for neutral AQ.…”

“…Consequently, the visible band of these AQ derivatives often features a characteristic multipeak structure. 5,7,8,13,19 The origin of multiple absorption maxima in quinoidic dyes is not necessarily unique, and proposals to explain this effect include aggregation, 20 tautomeric equilibrium, 21À23 and vibrational effects. 24,25 As we will demonstrate in this contribution, the latter explanation is by far the most appropriate for neutral AQ.…”

Photodecomposition of Aminoanthraquinone Disperse Dyes on Poly(ethylene terephthalate)

“…The fading characteristics of certain disperse dyes on polyester (PET) films are significantly different from those of the same dyes on cellulose acetate and nylon (I, 2). Thus, the shape of the absorption band, as measured by the ylx-peak ratio, changes most rapidly for the fading of the PET films (2). Furthermore, the activation energy of the fading reaction on PET is significantly lower than the corresponding values for other polymer films (3).…”

“…Deposition of organic-polymer coatings on to solid substrates from gas discharges has been the subject of a number of studies aimed principally at producing efficient dielectric films and protective coatings for metals (1-5). Limited application of this technique to paper, textiles, and glass and plastic sheets has produced improvements in adhesion, abrasion resistance, water repellency and dyeing properties (2,6). Treatment in glow discharges or corona discharges in the presence of non-polymerisable gases such as nitrogen, helium, oxygen and air improves the ink printability of polyethylene (7, 8), the bonding of polyethylene, polypropylene, nylon 6, Mylar polyester and several other plastics (9, lo), and cellulose paper (11, 12), the rate of dyeing and the shrink resistance of wool, and the breaking strength and wear resistance of various textiles (13,14).…”