Studies on Aminoanthraquinone Compounds V—Photochemistry of N-Methyl Derivatives in Solution

A study has been made of the action of near-ultraviolet and visible radiation on anaerobic solutions of 1-methylaminoanthraquinone and 1,4-bismethylaminoanthraquinone in different organic solvents. Fading in hydrogen-containing solvents occurs by reduction, but substantial fading is also observed in carbon tetrachloride solution.     

Photochemical Behaviour of Vat Dyes I—Reaction with the Polymer Substrate

The action of (a) near-ultraviolet and (b) short-wave ultraviolet radiation (mainly 253.7 nm) on nylon 6 and cellulose films dyed with one non-sensitising and two sensitising vat dyes has been studied. Photoreduction (in nitrogen) to the acid leuco derivative of the dye is observed only on exposure to 253.7-nm radiation. Vat dyes desensitise the degradation of cotton by 253.7-nm radiation, but there is no simple relation between this desensitising effect and their sensitising effect with near-ultraviolet and visible radiation. Degradation of vat-dyed cotton by 253.7-nm radiation is not increased by the reduction of the dye to the acid leuco form. Radical formation is unrelated to fibre degradation. The experimental evidence favours the concept of Kautsky's activated oxygen as an intermediary in the photosensitised degradation of cotton by near-ultraviolet and visible radiation, rather than that of hydrogen abstraction.     

Studies on Aminoanthraquinone Compounds IV–Photochemistry of some Simple Derivatives in Solution and on Polymer Films

An attempt has been made to determine the validity of the concept of the dye–ethanolsystem as a model for the photochemical degradation of textile materials sensitised by anthraquinone vat dyes. The action of (a) near–ultraviolet and visible radiation and (b) short–wave ultraviolet radiation (mainly 253–7 mμ) on anaerobic solutions of 1–aminoanthraquinone in ethanol, n–hexane, ethyl acetate, and carbon tetrachloride has been studied. Extensive fading of the dye occurs in these solvents with both typesof radiation. In the hydrogen–containing solvents characteristic spectra of reduction products of 1–aminoanthraquinone are produced, whereas in carbon tetrachloride there is extensive general destruction of the absorbing systems. The spectral changes occurring on the irradiation under anaerobic conditions of 1, 5–diaminoanthraquinone and 2–aminoanthraquinone in solution in ethanol and dyedon polymer films of N–methoxymethyl nylon, nylon 6. 6, and secondary cellulose acetate are compared. Only with 1, 5–diaminoanthraquinone and 1–aminoanthraquinone on N–methoxymethylnylon film are the changes on irradiation in dry nitrogen similar to those in ethanol. It is concluded that the photochemical behaviour ofanthraquinone dyes in organic solvents and in polymer systems can show considerable differences.     

Studies on Aminoanthraquinone Compounds

A study has been made of the action of near-ultraviolet and visible radiation on anaerobic solutions of 1- and 2-piperidinoanthraquin-ones in different organic solvents, and on polymer films dyed with these dyes. In the absence of oxygen, 1-piperidinoanthraquinone is reduced to the anthrahydroquinone on irradiation in solution and on nylon films. Under similar conditions, 2-piperidinoanthra-quinone is reduced to the anthrone in organic solvents, but the photochemical changes are more complex on polymer films. 1-Piperidinoanthraquinone doss not sensitise the photochemical degradation of nylon or cellulose acetate yarn. The results suggest that there is no definite relation between the ease of photoreduction of a dye and its ability to sensitise the photochemical degradation of textile fibres.     

Studies on Aminoanthraquinone Compounds

The action of (a) near-ultraviolet and visible radiation and (b) short-wave ultraviolet radiation (mainly 253.7 nm) on cellulose Alms dyed with three acylaminoanthraquinone vat dyes has been studied. Photoreduction to the acid leuco derivative of the dye is observed only on exposure to 253.7-nm radiation. One dye (l-benzamidoanthraquinone) has also been studied in anaerobic ethanolic solution. On exposure of this solution to near-ultraviolet and visible radiation, the dye is readily reduced to the anthrahydroquinone. Photo-reduction occurs readily in ethanol but with considerable difficulty on cellulose. There seems to be no correlation between the ability of the vat dye to sensitise the photochemical degradation of cellulose textiles and its ability to be photoreduced on cellulose.     

The effects of fluorescent substances on the photofading of colours. Part 4-photochemical interaction between fluorescent brightening agent of a pyrazoline type and 1,4-diaminoanthraquinone

The catalytic fading of 1,4-diaminoanthraquinone by a fluorescent agent of a pyrazoline type was demonstrated on irradiation with 366 nm light in aerobic acetonitrile solution. The quenching study with a singlet oxygen quencher and the chromatographic analysis of the photoproducts revealed a singlet oxygen intermediate. The fluorescent agent generated singlet oxygen in cellulose acetate films as well, causing a small amount of enhanced fading of the dye. No acceleration of the fading was observed either in ethanol or in nylon films. On 253 nm light irradiation the dye and the fluorescent agent suppressed each other's fading.     

Assembly of polyelectrolyte multilayers on nylon fibers

Non‐woven nylon fibers were investigated as a new type of substrate for the deposition of polyelectrolyte multilayers (PEM) thin films. PEM assembled from cationic poly(diallyldimethylammonium chloride) PDADMAC, and anionic Scarlet dye (λ_max absorbance = 510 nm) were deposited directly on Nylon fibers and characterized using a reflectometer spectrophotometer. Evidences of the film assembly are presented as well as a study of the factors controlling the growth of the PDAMAC/dye PEM film on the fiber. The relation between the sorption coefficient (K) and the scattering (S) extracted from the reflectance data is commonly used to represent the dye fixation or the dye content of a given textile fiber. The increase in K/S value at 510 nm was correlated with the dye deposition and was found to increase linearly with the number of layers. The effect of increasing number of layers, ionic strength of the solutions, concentration of chemicals, and dipping time on the film growth was investigated. Our results show that while increase in dye and PDADMAC concentrations from 0 to 1 mM enhance the deposition process, further increase in PDADMAC concentration to 50 mM led to a decrease in K/S value. The optimum salt concentration for the PDAMAC/dye film growth was found to be 0.5M and dipping times as short as 15 s were found to be sufficient for the deposition of the PEM. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3286–3290, 2006     

Studies of light fading of reactive dyes on cellophane

The ratios of extinction of the short wave (y) and the long wave (x) band in the visible region of the absorption spectra of three reactive dyes on cellophane film and also in aqueous solution, both in the presence and absence of urea, have been measured. Also changes in the ratio with time of exposure were determined. The ratio is found to increase with the concentration of the dye in the fibre and also in aqueous solution. Urea causes disaggregation. The state of aggregation of reactive dyes in cellophane is found to be intermediate between that obtained in a polyester–disperse dye system and nylon or cellulose acetate or cellulose–triacetate–disperse dye system.     

Dye sensitized artificial photosynthesis in the gas phase over thin and thick TiO2 films under UV and visible light irradiation

Perylene diimide based organic sensitizers capable of electron generation under illumination were used to initiate gas phase photo reduction reactions on TiO₂ thin and thick film surfaces. For comparison [Ru(Bpy)₃]²⁺ dye sensitizers were also studied. The photo reduction of CO₂ was carried out under static conditions in the gas phase. TiO₂ films were coated on hollow glass beads via a sol–gel procedure. Pt was incorporated on the films either by adding the precursor salt in the sol, Pt(in), or by wet impregnation of calcined film with an aqueous solution of the precursor salt, Pt(on). Organic sensitizers were incorporated on the films by wet impregnation of the film from an aqueous solution. Under UV illumination, the methane yields of platinized TiO₂ thin films decreased in the following order: Pt(on)·TiO₂ > Pt(in)·TiO₂ > TiO₂. The presence of organic sensitizers inhibited the catalytic activity of pure and platinized TiO₂ thick films under UV illumination. The relative enhancement of the reaction yields in the presence of the organic sensitizer under visible light illumination depended on the presence of Pt as well as the incorporation method of Pt in the TiO₂ structure. The reaction yields were better when Pt was impregnated on the TiO₂ film than when Pt was incorporated in the Ti sol. On the other hand, pure or platinized TiO₂ under visible light illumination was totally inactive indicating the role of the organic dye in generating catalytically active electrons under visible light.     

Effect of Laser Radiation on Dyed Polymeric Films

Abstract

Destruction of the thin dyed polymeric films under the action of resonant and non-resonant laser radiation has been investigated. It is shown thai laser stability of dyed polymers depends on the type of incorporated dye and it is independent of film thickness and dye concentration at the same powers of absorbed laser radiation. Moreover, laser stability of polymeric films with chemically bonded dye is higher than the polymer stability with dissolved dye. Comparative analysis showed that the polymer laser stability is determined by the kinetics of the polymer thermodegradation. which results in the appearance and accumulation of the products absorbing laser radiation. It is established that resonant irradiation of dyed polymers is considerably more efficient for polymer destruction than the nonresonant one.     

Functionalization of polypropylene film by radiation grafting of acryloyl chloride and subsequent esterification with Disperse Red 1

Polypropylene (PP) films were grafted with acryloyl chloride by γ‐irradiation, and the grafted films were reacted with an azo dye, Disperse Red 1. The films were characterized by X‐ray diffraction, scanning electron microscopy, atomic force microscopy, and differential scanning calorimetry. It was found that the grafting takes place first on the film surface, and with increase in the radiation dose the grafting penetrated inside of the film, decreasing the crystallinity of the PP film. The surface of the films was homogeneous, and a mesophase was observed for the film grafted with the dye through a polarized optical microscope. The dye underwent trans to cis photoreaction, whereby the red films became colorless by the irradiation of UV light at room temperature, although the color was recovered on standing, and more quickly when heated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 172–178, 2004     

Regulation of dye assembly within wet and dry nafion films

Different forms of Nafion films were prepared and used to exchange phenothiazine and phenazine dye cations. The monomer dye molecules are emittive and the protonated and aggregated dye molecules are nonemittive. A spectrophotometer and spectrofluorometer were used effectively to identify these molecules in the adsorbed state and the control of different forms of dye molecules by Nafion film was clearly established. Protonation of the dye molecules occurred mainly in the proton-exchanged dry Nafion film (H⁺—Nf), whereas dimerization of dye molecules was predominant in the sodium-exchanged dry Nafion film (Na⁺–Nf). The higher acidity and narrow ionic cluster and interfacial regions of the dry Nafion films were found to control the protonation and dimerization of dye molecules. The dyes were predominantly in monomeric form in the wet H⁺– and Na⁺–Nf films. When the Na⁺–Nf film was in a wet condition, the ionic cluster and interfacial regions expanded to form a more open structure. When large hydrophobic organic cations like tetrabutyl ammonium ions (Bu₄N⁺) and tetraethyl ammonium ions (Et₄N⁺) were exchanged into the Nafion film, the film structure was totally controlled by these organic cations and, consequently, controlled the monomeric and dimeric forms of dyes in the film. The dye adsorbed dry H⁺– and Na⁺–Nf films may find applications in acid–base sensors. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 777–787, 1997     

Preparation of conductive nylon 6 film

Electrically conducting nylon 6 films was prepared by introducing amide group or cyan group into the nylon 6 film and then introducing Cu_xS, which is known as the p-type semiconductor, into the grafted nylon films. The graft copolymerization of acrylamide (AM) and acrylonitrile (AN) onto nylon 6 film was investigated using ceric salt as the initiator. The graft yield was influenced by the concentration of ceric salt, sulfuric acid and monomer, and the reaction time. The optimum conditions for the introducing of Cu_xS were studied. Electrical conductivity of Cu_xS-treated nylon film was found to be higher by order of 10⁹ than that of the original nylon 6 film, and then properties of the resulting modified films were investigated.     

Deformation‐Induced Color Changes in Melt‐Processed Polyamide 12 Blends

Blends of polyamide 12 and small amounts (0.15–1 wt%) of the excimer‐forming fluorescent dye 1,4‐bis(α‐cyano‐4‐octadecyloxystyryl)‐2,5‐dimethoxybenzene (C18‐RG) are produced by melt‐processing. While green monomer fluorescence from well‐individualized chromophores is observed at low dye concentration (0.15%), higher dye concentrations lead to aggregation of the dye so that the emission characteristics are dominated by red excimer fluorescence. Upon mechanical deformation of samples with appropriately selected dye content (0.25 wt%), a pronounced mechanochromic effect can be observed, which manifests itself through a mechanically induced transformation from excimer‐dominated to monomer‐rich emission. The monomer to excimer emission ratio I_M/I_E is increased by a factor of up to 2 in a step‐wise manner when samples are uniaxially deformed past the yield point.

     

Analysis of keratin films as screening tools for predicting the efficacy of potential hair dyes

The technology for generating high quality keratin films has recently advanced and led to their implementation in a variety of applications. As an initial step toward investigating the films as a screening tool for predicting the efficacy of potential hair dyes, CI Acid Orange 7 was applied to a set of opaque and translucent films. Overlaid time‐of‐flight secondary ion mass spectrometry images arising from protein and dye fragments revealed that dye uniformly penetrated both film types. Results also showed that the relative concentration of dye in each film complemented outcomes from ultraviolet‐visible analysis and revealed that the translucent film contained a higher dye concentration. Scanning electron microscopy analysis of film morphology suggested that the observed difference was due to the higher porosity of the opaque film, which facilitated dye desorption during the rinsing step. Consequently, the translucent film was judged to be a better substrate for screening potential new hair dyes.     

Photocatalytic activity of undoped and sulfur-doped TiO2 films grown by MOCVD for water treatment under visible light

Titanium dioxide ceramic coatings have been used as catalysts in green technologies for water treatment. However, without the presence of a dopant, its photocatalytic activity is limited to the ultraviolet radiation region. The photocatalytic activity and the structural characteristics of undoped and sulfur-doped TiO₂ films grown at 400 °C by metallorganic chemical vapor deposition (MOCVD) were studied. The photocatalytic behavior of the films was evaluated by methyl orange dye degradation under visible light. The results suggested the substitution of Ti⁴⁺ cations by S⁶⁺ ions into TiO₂ structure of the doped samples. SO₄^2? groups were observed on the surface. S-TiO₂ film exhibited good photocatalytic activity under visible light irradiation, and the luminous intensity strongly influences the photocatalytic behavior of the S-TiO₂ films. The results supported the idea that the sulfur-doped TiO₂ films grown by MOCVD may be promising catalysts for water treatment under sunlight or visible light bulbs.     

Synthesis and characterizations of magnetite nanocomposite films for radiation shielding

Polyvinyl alcohol (PVA) films containing magnetite Fe₃O₄ nanoparticles have been prepared by co‐precipitation method for use in gamma ray shielding and protection. Characterizations of the magnetite/PVA nanocomposite films were investigated by X‐ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectroscopy, and magnetization measurements. TEM images showed that the synthesized magnetite particles had about 6–11 nm dimensions. Optical study's results revealed that the optical energy band gaps of thin films range between 1.82 and 2.81 eV at room temperature using UV–visible absorption spectroscopy. The saturation magnetization (MS) value measured by vibrating sample magnetometer VSM was found to be 8.1 emu/g with superparamagnetic nature. The radiation shielding properties such as linear attenuation coefficients (μ ) and half‐value thickness (HVT) for the magnetite nanocomposite films have been obtained experimentally for different photon energies. The results imply that these nanocomposites films are promising radiation shielding materials. POLYM. COMPOS., 38:974–980, 2017. © 2015 Society of Plastics Engineers     

Quantum Efficiency Measurements of Fading of some Disperse Dyes in Nylon and Polyester Films and in Solution

Several anthaquinone and azo disperse dyes adsorbed on films of polyester and nylon 6. 6 and dissolved in a mixture of acetone and water have been faded by various lines in the visible spectrum, and the quantum yields (φ) determined by means of the Parker-Hatchard potassium ferrioxalate actinometer. φ for adsorbed dye lies between ca 10^-4 and 10^-6, decreasing with increase in exposure time, probably owing to the presence of associated dye, and with increase in wavelength of illumination. Values for dye in solution are 20–60 times as high as those for adsorbed dye. The low values for adsorbed dye are the result of a combination of several factors, including association of dye, retardation of gaseous diffusion by the substrate, and the shield or cage effect of the surrounding polymer substrate.     

The Determination of Diffusion Coefficients as a Function of Concentration for Dyes in Fibres

A method of determining the dependence on dye concentration of the diffusion coefficient of dyes in fibrous substrates has been developed, based on an approximation method of Crank, in which the amount of dye adsorbed by the fibre is measured colorimetrically as a function of time. The method has been applied to two dyeing systems, the direct dye Chlorazol Sky Blue FF (C. I. Direct Blue 1) on rayon and the acid dye Naphthalene Scarlet 4R (C. I. Acid Red 18) on nylon 6. 6. The results are in good agreement with those of R. H. Peters et al. for the same dyes and substrates, although Peters used films and not fibres and determined diffusion coefficients by an experimentally more complex method that appears impractical for fibres, the film being sectioned and the dye concentration measured as a function of distance with a microdensitometer.     

Fading characteristics of a disperse dye on cellulose triacetate, polyester and nylon under monochromatic light radiation

Light fastness of CI Disperse Blue 165 dye on cellulose triacetate, polyester and nylon fabric substrates exposed to monochromatic light was examined on a radiant energy basis. The action spectra indicated a strong effect on the substrate-fading characteristics: nylon exhibited poorer light fastness in the visible and ultraviolet light range than polyester and cellulose triacetate. Two specific fading peaks were found for the nylon substrate, which were different to those found for the polyester and cellulose substrates. It was shown that polyester exhibited the best light fastness properties overall. The colour changes in the fading process suggested that the fading products of the dye on nylon (where reduction occurred) were different from those on the polyester and cellulose triacetate substrates (where oxidation occurred).