Synthesis of Azo Disperse Dyes with High Absorption for Efficient Polyethylene Terephthalate Dyeing Performances in Supercritical Carbon Dioxide

Supercritical carbon dioxide dyeing (SCDD) not only enables strong dyeing performance for a versatile range of polymer material but is also regarded as a green chemical media due to its low environmental impact as well as low risk of product denaturation. Over the decades, azo disperse dyes have been revealed to be efficient dyes and represent the wide majority of dyeing material. Azo dyes possess a wide variety of functional groups to optimize dye synthesis and tune the light absorption properties. Using SCDD, end-chain of different lengths, and functional group exhibiting various electronic affinity, six disperse red azo dyes were synthesized to investigate dyeing performances as woven fabric type, color strain, and color fastness after dyeing are discussed. Dye structure synthesized through a coupling reaction was confirmed by ¹H NMR and mass spectroscopy. We found that the light absorption wavelength and absorption coefficient value variation are associated to the nature of the functional group. From the color strength values of the polyethylene terephthalate woven after dyeing, we find that the fiber host and dye dopant chemical structure greatly influence the dyeing process by providing enhanced woven, color strain, and color fastness. In comparison with commercial products, our approach not only improves the dyeing process but also guarantees a strong resistance of the dyed product against water, detergent, perspiration, abrasion, and friction.

Delivery of oxaliplatin to colorectal cancer cells by folate-targeted UiO-66-NH2

Oxaliplatin is being used in different malignancies and several side effects are reported for patients taking Oxaliplatin, including peripheral neuropathy, nausea and vomiting, diarrhea, mouth sores, low blood counts, fatigue, loss of appetite, etc. Here we have developed a targeted anticancer drug delivery system based on folate-conjugated amine-functionalized UiO-66 for the delivery of oxaliplatin (OX). UiO-66-NH₂ (U) and UiO-66-NH₂-FA(FU) were pre-functionalized by the incorporation of folic acid (FA) into the structure via coordination of the carboxylate group of FA. The FTIR spectra of drug-loaded U and FU showed the presence of new carboxylic and aliphatic groups of OX and FA. Powder X-ray diffraction (PXRD) patterns were matched accordingly with the reference pattern and FESEM results showed semi-spherical particles (115-128 nm). The evaluated amounts of OX in U and FU were calculated 304.5 and 293 mg/g_, respectively. The initial burst release of OX was 15.7% per hour for U(OX) and 10.8% per hour for FU(OX). The final release plateau gives 62.9% and 52.3% for U(OX) and FU(OX). To evaluate the application of the prepared delivery platform, they were tested on colorectal cancer cells (CT-26) via MTT assay, cell migration assay, and spheroid model. IC₅₀ values obtained from MTT assay were 21.38, 95.50, and 18.20 μg/mL for OX, U(OX), and FU(OX), respectively. After three days of treatment, the CT26 spheroids at two doses of 500 and 50 μg/mL of U(OX) and FU(OX) showed volume reduction. Moreover, the oxidative behavior of the prepared systems within the cell was assessed by total thiol, malondialdehyde, and superoxide dismutase activity. The results showed that FU(OX) had higher efficacy in preventing the growth of CT-26 spheroid, and was more effective than oxaliplation in cell migration inhibition, and induced higher oxidative stress and apoptosis.

Synthesis and degradation of branched, photo-labile poly(acrylic acid) and polystyrene

We present the synthesis, characterization and photolytical degradation of branched photo-responsive poly(acrylic acid) and polystyrene using free radical polymerization of acrylic acid/styrene in the presence of a newly synthesized asymmetric o-nitrobenzyl-based crosslinker and different amounts of dodecanethiol (DDT) as a chain transfer agent.

Decolorization and reusing of PET depolymerization waste liquid by electrochemical method with magnetic nanoelectrodes

This work is aimed at electrochemical decolorization of real waste liquid which obtained in the PET depolymerization process. Firstly, PET fabrics were glycolysized by utilizing excess ethylene glycol (EG). Then, the glycolysis product was mixed with water and purified through repeated crystallization to get bis(2-hydroxyethyl) terephthalate (BHET) crystal. At last, the waste liquid of the depolymerization process was electrochemical decolorized by utilizing chitosan/Fe₃O₄ nanoparticles as the dispersed electrodes under a DC voltage. The UV-Vis absorptions at 338, 531, and 635 nm which were due to the dyes in the waste liquid decreased with the electrolysis time. In contrast, slight change of absorption of EG (at 322 nm) indicated that EG was not destroyed in the electrolytic process. The variation of color removal efficiency with dosage of chitosan/Fe₃O₄ nanoparticles, applied voltage, concentration of electrolyte, pH and electrolytic time were investigated. The max color removal efficiency was 87.24%. PET fabrics were depolymerized by using the decolorized waste liquid or mixture of decolorized waste liquid and EG (1:1 v/v), and the yields of BHET were 72.3% and 76.6%, respectively. The products were BHET without dyes which were confirmed by DSC and FTIR spectroscopy. Graphical abstract.

Decoloration of waste PET alcoholysis liquid by an electrochemical method

Disperse Red 60 simulated polyester alcoholysis liquid decoloration by electro-Fenton with Fe₃O₄ catalyst was studied. The influences of the main operating parameters such as catalyst dosage (0.3-0.9 g/L), current density (60-120 mA/cm²) and pH (1-7) were optimized by response surface methodology (RSM) based on Box-Behnken surface statistical design (BBD). In optimal conditions, the initial concentration of 25 mg/L disperse red polyester alcoholysis liquid was catalyzed by 0.6 g/L Fe₃O₄, and the decoloration efficiency was 97.18% with the current density of 90 mA/cm² and initial pH of 4.6. There was a relative error of 1.18% with the predicted model when the predictive value was 98.25% under the same conditions. In addition, ultraviolet-visible absorption spectra (UV-Vis), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) were used to study the degradation mechanism during decoloration. The intermediates were identified and the proposed degradation pathways were investigated by liquid chromatography-mass spectrometry (LC-MS) analysis.

The potential use of recycled PET bottle in nanocomposites manufacturing with modified ZnO nanoparticles capped with citric acid: preparation, thermal, and morphological characterization

We devised a fast and facile potential practical application by incorporating the guest ZnO nanoparticles (NPs) into poly(ethylene terephthalate) (PET) as a host polymer that recycled by dissolution/reprecipitation method.