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Modified curcumin, which has the advantages of low toxicity, high solubility, and little color change after modification, is very suitable for nonaqueous supercritical carbon dioxide cotton dyeing. However, the existing curcumin modification technology focuses on improving its solubility. Modified curcumin is directly adsorbed onto cotton fabrics, and the main interaction forces are van der Waals forces, which causes the poor fastness of modified curcumin to dyed cotton fabrics. In this study, reactive groups (hydroxyalkyls) were introduced into curcumin to enhance its fastness to cotton fabrics. The results showed that, similar to alkyl groups, hydroxyalkyl groups can enhance the color depth of dyed cotton fabrics by elevating the solubility of modified curcumin in supercritical carbon dioxide. The higher the solubility of modified curcumin in supercritical carbon dioxide was, the higher the K/S value of the dyed cotton fabric. Furthermore, the hydroxyl groups on the modified curcumin could form ether bonds with the hydroxyl groups on cotton fabrics. Therefore, the washing and rubbing fastness of hydroxyalkyl-curcumin-dyed cotton fabric was better than that of alkyl-curcumin-dyed cotton fabric. [ABSTRACT FROM AUTHOR]

In this paper, using carbon dioxide as a dyeing medium, some basic color and mechanical behaviour data for yak hairs were firstly obtained with different parameters. The effects of system temperature, pressure, time and depressurization rate on yak hairs were investigated in terms of the color strength, the short fiber content, the breaking strength and the elongation at break. The results indicated that the short fiber content of yak hairs was increased with the raising of system temperature, pressure, time as well as depressurization rate, while the breaking strength and the elongation at break of yak hairs were decreased with the increase of system temperature, time as well as depressurization rate. Moreover, supercritical carbon dioxide for the fracture mechanism of yak hairs was proposed based on the Bernoulli’s principle and Boyle’s Law. [ABSTRACT FROM AUTHOR]

Traditional cotton water dyeing has a considerable ecological impact because of the use of water, but the available anhydrous cotton dyeing technologies cannot balance low recyclable energy consumption and excellent dyeing effects. In this study, a recyclable anhydrous cotton dyeing technology was designed and implemented by mixing supercritical carbon dioxide, dimethyl sulfoxide, and ethanol for the first time. Compared to the existing anhydrous cotton dyeing technologies, the novel technology could simultaneously obtain low recyclable energy consumption and excellent dyeing effects, such as dye penetration, washing and crocking fastness, levelness, color depth control and color matching. The dye fixations of reactive dyes in the novel technology are 5.1%–26.4% higher than those in traditional water dyeing. Meanwhile, the energy consumption of the novel technology is only 70% of that of traditional water dyeing, and the comprehensive cost of materials and energy of the novel technology is only 56% of that of traditional water dyeing. It is a new green option with low energy consumption for cotton dyeing. [Display omitted] • No water involves in SC-CO 2 /EtOH/DMSO multi-medium dyeing. • All dyeing media of SC-CO 2 /EtOH/DMSO multi-medium dyeing are recyclable. • SC-CO 2 /EtOH/DMSO multi-medium dyeing is a low-energy process. • SC-CO 2 /EtOH/DMSO multi-medium dyeing has excellent dyeing effects. [ABSTRACT FROM AUTHOR]

• Changes of absorbances and melting points were not related to color differences. • Changes in solubilities and affinities were fundamental reason for color differences. • Degree of esterification had greatest effect on disperse red 167:1′s color difference. [Display omitted] The reason of color differences caused by different degree of esterification disperse dyes were investigated by disperse orange 30, disperse red 167:1, disperse blue 79:1 with different degree of esterification. The results showed that the changes of light absorbance abilities and melting points caused by ester groups had no obvious correlation with the color differences caused by ester groups. The changes in the solubilities and affinities caused by the ester groups were the fundamental reason for the changes in the dyeing properties of disperse orange 30, disperse red 167:1 and disperse blue 79:1. As a joint result of the decrease in solubilities and affinities, the dye sorption in polyethylene terephthalate of unesterified disperse orange 30, unesterified disperse red 167:1 and unesterified disperse blue 79:1 were reduced by 37.7%, 83.6% and 54.6%, respectively, compared with those of the corresponding completely esterified dyes. [ABSTRACT FROM AUTHOR]

Supercritical carbon dioxide (scCO 2) is commonly used as an excellent solvent in chemical reactions and dyeing fields because of its advantages. In this work, three coumarin and 1,8-naphthalimide fluorescent dyes (DAMC , NP-NH , and NP-dimethyl) were successfully constructed on the basis of the Au/titanium dioxide (Au/TiO 2) catalytic reduction of nitro in scCO 2 instead of SnCl 2 /hydrochloric acid solution, and their structures were confirmed correctly by mass spectrometry (MS) and nuclear magnetic resonance (NMR). The cleaner synthesis and dyeing polyester fabrics of coumarin derivative (DAMC) in the presence or absence of N-methyl-pyrrolidone (NMP) were first studied by employing stepwise and synchronous methods. All results for DAMC indicated that the synchronous synthesis and dyeing method is more beneficial. Here, the synchronous synthesis and dyeing polyester fabrics of 1,8-naphthalimide derivatives (NP–NH and NP-dimethyl) in scCO 2 were also investigated. Through the comprehensive analysis of color strength (K/S) value and fixation rate, the optimal temperatures and pressures of synthesis and dyeing for NP-NH and NP-dimethyl were obtained in the absence or presence of NMP. The dyed fabrics with NP-NH and NP-dimethyl exhibited yellow or yellowish-brown in daylight and bright fluorescent yellowish-green in ultraviolet light. All results showed that the clean production of fluorescent dyes (DAMC , NP-NH , and NP-dimethyl) can be realized by the hydrogenation of nitro with efficient Au/TiO 2 catalyst in scCO 2 , meanwhile, the synchronous synthesis and dyeing method was proposed for the synthesized dyes. The realization of synchronous synthesis and dyeing fabrics for fluorescent dyes in scCO 2 is an effective way to prevent environment pollution brought by the processes of synthesis and dyeing. Thus, the constructing and dyeing strategy of fluorescent dyes will be beneficial to the sustainable development of environment. In this study, three coumarin and 1,8-naphthalimide fluorescent dyes (DAMC , NP-NH , and NP-dimethyl) were successfully constructed on the basis of the Au/titanium dioxide (Au/TiO 2) catalytic reduction of nitro in scCO 2 , and their structures were confirmed correctly by mass spectrometry (MS) and nuclear magnetic resonance (NMR). The cleaner synthesis and dyeing polyester fabrics of coumarin derivative (DAMC) in the presence or absence of N-methyl-pyrrolidone (NMP) were first studied by employing stepwise and synchronous methods. All results for DAMC indicated that the synchronous synthesis and dyeing method is more beneficial. Here, the synchronous synthesis and dyeing polyester fabrics of 1,8-naphthalimide derivatives (NP–NH and NP-dimethyl) in scCO 2 were also investigated. Through the comprehensive analysis of color strength (K/S) value and fixation rate, the optimal temperatures and pressures of synthesis and dyeing for NP-NH and NP-dimethyl were obtained in the absence or presence of NMP. The dyed fabrics with NP-NH and NP-dimethyl exhibited yellow or yellowish-brown in daylight and bright fluorescent yellowish-green in ultraviolet light.Synopsis: The synchronous synthesis and dyeing polyester fabrics of coumarin and 1,8-naphthalimide dyes in scCO 2 were also investigated. [Display omitted] • Three coumarin and 1,8-naphthalimide fluorescent dyes were constructed in scCO 2 media. • The synchronous synthesis and dyeing method was proposed for the synthesized dyes in scCO 2. • The constructing and dyeing strategy of fluorescent dyes is beneficial for the sustainable development of environment. [ABSTRACT FROM AUTHOR]

Technology of supercritical carbon dioxide (scCO 2) dyeing has been used in dyeing synthetic and natural fibers. It is important to understand the scCO 2 dyeing mechanism owing to the possibility of using this knowledge to design dyes that are suitable for scCO 2 dyeing. Here, using the N-site and 4-site modification of 1,8-naphthalimide matrix, six fluorescent dyes (1 , 2 , 3 , 4 , 5 , and 6) with fluorescent properties were synthesized; dyeing performance and fluorescent images indicate that all the synthesized dyes can be utilized for scCO 2 dyeing wool fibers. Therefore, the dyed wool fibers possess not only conventional dyeing characteristics but also luminescent properties. Especially, the dyed wool fibers with solid free fluorescent dye 2 exhibit strong yellow-green fluorescence. Owing to the lack of proper fixation process, the fixation rate of these six fluorescent dyes on wool fibers was not relatively high. Thus, the dye 7 with an active group N-hydroxysuccinimide (NHS) was synthesized to improve the binding force between dyes and wool fibers and it can react with the –NH 2 group in wools, which results in that the fixation rate of the synthesized dye 7 reaches approximately 91% through chemical combination. Mass spectra prove that the byproduct of 7 reacting with the amino group of wool fibers is not corrosive to dyeing equipment, which realizes the eco-friendly fluorescent dyeing of wool fibers in scCO 2. Our results proved that the fluorescent dyes with conjugated system can overcome the problem of fluorescence quenching in natural fibers. Meanwhile, our strategy of constructing fluorescent dyes and the proposed dyeing mechanism will be helpful to develop reactive disperse dyes that are suitable for scCO 2 dyeing. [Display omitted] • The dyed wool fibers with solid free fluorescent dye 2 showed strong yellow-green fluorescence. • Photophysical properties and dyeing mechanism of dyes suitable for the scCO 2 dyeing wool fibers were investigated. • The fixation rate of new reactive disperse dye 7 reached approximately 91% through chemical combination. [ABSTRACT FROM AUTHOR]