Laijiu Zheng

A turn-on and colorimetric metal-free long lifetime fluorescent probe and its application for time-resolved luminescent detection and bioimaging of cysteine

A turn-on and colorimetric metal-free long lifetime fluorescent probe for sensing Cys has been synthesized. Utilizing the long emission-lifetime of DCF-MPYM, the time-resolved luminescent assay of DCF-MPYM-thiol for sensing Cys was realized successfully. DCF-MPYM-thiol can realize confocal and time-resolved microscopy bioimaging for Cys in living cells.

Optimization of an ecofriendly dyeing process in an industrialized supercritical carbon dioxide unit for acrylic fibers

The feasibility of using supercritical CO2 as a cleaning dyeing medium to dye acrylic fibers was investigated on an industrialized unit. The influence of dyeing temperature, dyeing pressure, dyeing time, and dye concentration on the K/S values of acrylic fibers was examined using the fractional factorial design of experiments. A second-order polynomial model was established to analyze the interactions between distinct parameters and to obtain the optimal K/S values. The results showed that an excellent dyeing effect of acrylic fibers was obtained in the industrialized supercritical CO2 unit, but the dyeing effect was easily affected by variations of the dyeing parameters. In the experimental range, a calculated K/S value could be up to 6.14 with the dyeing temperature of 100℃, dyeing pressure of 26 MPa, dyeing time of 60 min, and dye concentration of 3%. The dyed acrylic fibers presented good color fastness to washing, rubbing, and light. Furthermore, a commercially acceptable levelness and reproducibility for acrylic fibers were obtained in the supercritical CO2 dyeing process.

Investigations on the effect of carriers on meta-aramid fabric dyeing properties in supercritical carbon dioxide

Dyeing of meta-aramid fabric with dimethyl terephthalate, ethyl alcohol and CINDYE DNK as carriers was investigated in supercritical carbon dioxide fluid. The effect of different carriers on the dyeing properties of meta-aramid fabric with Disperse Blue Black 79, Disperse Rubine H-2GL, and Disperse Yellow EC-3G was examined by measuring the color strength with different dyeing temperatures, dyeing pressures, dyeing times, dye concentrations, carrier concentrations and carbon dioxide flows. The results showed that the carriers added in supercritical carbon dioxide were beneficial to the diffusibility of disperse dye molecules into the amorphous region of the meta-aramid fiber, thereby improving its dyeability. In these three carriers, the K/S values of the dyed meta-aramid samples with ethyl alcohol were higher than the samples with dimethyl terephthalate, and the greatest improvement on K/S values appeared upon adding CINDYE DNK in supercritical carbon dioxide. In addition, the dyed meta-aramid fabrics in supercritical carbon dioxide presented good wash fastness, rub fastness and light fastness, which was rated at 4–5.

Optimization of Eco-Friendly Reactive Dyeing of Cellulose Fabrics Using Supercritical Carbon Dioxide Fluid with Different Humidity

ABSTRACT An eco-friendly dyeing of cotton fabrics with Reactive Golden Yellow K-2RA was carried out using supercritical carbon dioxide fluid with different humidity. Effect of dyeing temperature, pressure, time, dye concentration, and gas humidity on the dyeing properties of cellulose was investigated. The results indicated that good dyeing effect was achieved because of the nucleophilic substitution reaction of monochlorotriazine reactive group in Reactive Golden Yellow K-2RA and hydroxyl functional groups in cotton. The color strength of dyed samples was improved with the variation of dyeing conditions. An optimized eco-friendly dyeing of cellulose fabrics was recommended with a dyeing temperature of 90°C, a dyeing pressure of 20 MPa, a dye concentration of 5%, and gas humidity of 5% for 60 min in supercritical carbon dioxide fluid. Furthermore, acceptable washing, rubbing and light fastness rated over 4 were obtained.

Effect of treatment temperature on structures and properties of flax rove in supercritical carbon dioxide

In this study, flax rove was treated in supercritical carbon dioxide. The effect of different treatment temperatures on the surface morphology, chemical and crystal structures, and thermal properties, as well as isolated compounds of flax rove, were investigated by employing scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal analysis, and nuclear magnetic resonance (NMR), respectively. The results showed that more mild grooves and stripes appeared on the surface of the treated flax fibers after supercritical carbon dioxide treatment. FT-IR spectra showed that hydrolysis of macromolecule of flax fibers occurred, producing a C≡C group. XRD spectra confirmed that the crystallinity of the treated flax samples was gradually increased with the raising of treatment temperature. Simultaneously, thermo gravimetric analyzer (TGA), differential thermal gravity (DTG) and differential scanning calorimetry (DSC) analysis indicated that the thermal properties of flax rove were improved with the increase of treatment temperature. In addition, NMR analysis proved that lignin and the monosaccharide composition of isolated compound were extracted from flax rove. Moreover, a predominance of β–O–4’ arylether linkages, followed by β–5’ phenylcoumaran and β–β’ resinol-type linkages for lignins of isolated compound was shown in NMR. Therefore, the results confirmed that it is technically feasible to using supercritical carbon dioxide to conduct the scouring and bleaching of flax rove.