Compared with traditional water dyeing, supercritical carbon dioxide (scCO2) dyeing is more environmentally benign. scCO2 is widely used as a green solvent in dyeing synthetic fibers. However, studies involving dyeing natural fibers in scCO2 are scarce. The commonly used methods result in corrosion of the dyeing equipment. Thus, the development of new special dyes suitable for scCO2 dyeing is necessary; in addition, insight into the dyeing mechanism is important in promoting the design and synthesis of dyes for wool fibers in scCO2. On the basis of our previous work, a possible dyeing mechanism in which the dyes exhibit hydrophobic interaction with keratins is proposed. The NN bond twisting in azo dyes promotes the dyes embedding into the spaces of the alpha helices in proteins. According to the proposed mechanism, two new azo disperse dyes (azo thiazole-N­(CH3)2 and azo thiazole-OCH3 ) were synthesized; these dyes enable the dyeing of wool fibers in scCO2. Meanwhile, the introduction of a succinimidyl ester group results in the fixation rate of the new reactive disperse dyes azo thiazole-NHS and azo-NHS reaching 100%. The byproduct of azo thiazole-NHS and azo-NHS reacting with the amino group of wool keratin is not corrosive to the dyeing equipment, thus enabling an eco-friendly dyeing process for wool fibers. Our strategy of introducing a succinimidyl ester reactive group will promote the development of new functional disperse dyes suitable for dyeing wool fibers in scCO2.

Structure and properties of polyethylene terephthalate were characterized by SAM, Fourier transform infrared spectrometry, X-ray diffraction, and thermal analysis to evaluate the effect of supercritical CO 2 on the structural behavior. The dynamic shrinking behavior of polyethylene terephthalate was analyzed using the Kelvin-Voigt model. The results indicated that uneven and significantly different surface of the polyethylene terephthalate fiber was displayed since the spinning oil and other additives added in spinning process were rinsed in supercritical CO 2. The slight shifts for the characteristic bands of polyethylene terephthalate in Fourier transform infrared spectrometry were observed due to some rearrangements and re-crystallizations of the molecule chains after supercritical CO 2 treatment. Simultaneously, the crystallinities and the fastest thermal decomposition temperatures of polyethylene terephthalate were improved slightly from 80 °C to 120 °C in supercritical CO 2. Furthermore, the shrinkage of the treated polyethylene terephthalate samples was increased gradually from 2.73% to 3.35% with the temperature raising.

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In this study, NP-indometacin, which was based on the twophoton naphthalimine, was designed and synthesized. The anti-inflammatory material indometacin was introduced into NP-indometacin so that the toxicity of this fluorescent dye was reduced when applied to living organisms. NP-indometacin had high fluorescence quantum efficiency (0.98 in DMSO), a large Stokes shift (> 77 nm) and feasible two-photon action cross section (45 GM in DMSO). NP-indometacin was utilized for the fluorescence imaging of living cells, and the high cell viability rate (> 80%) indicated that this material had low toxicity in living organisms. NP-indometacin was used to dye absorbable collagen surgical suture and constructed fluorescent surgical suture. It was found by one-and two-photon fluorescence imaging that NP-indometacin distributed uniformly both outside and inside the sutures. Therefore, the straightforward synthesis of NP-indometacin and the wide availability of its constituents mean that it could both be highly useful for the observation of the healing of wounds and as a fluorescent warning material that is used in vivo.[a] Dr.