Ling-hua Zhuang

Salt-free dyeing of ramie fabric with an amino-terminated hyperbranched polymer

A new amino-terminated hyperbranched polymer (at-HBP) was synthesized, and its salt-free dyeing property on ramie fabric was studied. The structure and molecular weight of at-HBP were established by Fourier transform infrared spectrometer, H nuclear magnetic resonance and gel permeation chromatography. The untreated ramie fabric and modified ramie fabrics were characterized by an X-ray diffraction (XRD) and field emission scanning electron micrograph (FE-SEM). XRD results showed a transformation of the crystalline structure from ramie cellulose I to cellulose II allomorph during mercerization and epichlorohydrin modification, and the crystalline structure of cellulose II was maintained with an obvious crystallinity index increase after at-HBP modification. FE-SEM results confirmed that at-HBP was successfully grafted onto the fabric surface. Dyed with reactive dye C.I. reactive Blue 4, the color strength of the at-HBP-modified fabric was enhanced, even when dyeing was carried out without the electrolyte. The washing and rubbing fastness of the salt-free dyeing of fabrics was also good compared with those obtained by conventional dyeing. The adsorption isotherm of C.I. reactive Blue 4 on modified fabric was examined and found to follow a Langmuir-type adsorption model. The at-HBP modification mechanism of ramie fabric and dyeing mechanism with reactive dye were suggested.

Performances of ramie fiber pretreated with dicationic imidazolium ionic liquid

The chemical structure of a new gemini dicationic imidazolium ionic liquid, 3,3′-[1,2-ethanediylbis (oxy-2,1-ethanediyl)]-bis[1-methyl-imidazolium]-dibromide (PEG150-DIL) was established by 1H-NMR and elemental analyses. Then, PEG150-DIL was applied to pretreat ramie fiber. PEG150-DIL treated ramie fiber was characterized by FT-IR, XRD, DSC-TG and FE-SEM. Finally, the mechanical and dyeing properties of PEG150-DIL pretreated ramie fibers were studied. The optimum condition of PEG150-DIL modification was carried out at 100 °C for 30 min. The color strength increased obviously with the duration time and temperature of the PEG150-DIL. The tensile strength and strength retention of PEG150-DIL -treated ramie fibers decreased with the increase of pretreating time and temperature. The tensile strength retention was 86.20 % under optimal PEG150-DIL pretreating condition (100 °C, 30 min).

3,3′-Dimethyl-1,1′-(butane-1,4-di­yl)diimidazolium bis­(tetra­fluoro­borate)

The title compound, C12H20N4 2+·2BF4 −, was prepared by the anion exchange of a dibromide ionic liquid with sodium tetrafluoroborate. The asymmetric unit contains one half of the imidazolium cation, which lies about an inversion centre at the mid-point of the central C—C bond of the linking butyl chain. The two planar imidazole rings (r.m.s. deviation = 0.0013 Å) are strictly parallel and separated by 2.625 (7) Å [vertical distance between the centroids of two imidazole rings], giving the molecule a stepped appearance. In the crystal structure, intermolecular C—H⋯F hydrogen bonds link the cations and anions, generating a three-dimensional network.

Preparation, characterization, adsorption kinetics and thermodynamics of chitosan adsorbent grafted with a hyperbranched polymer designed for Cr(VI) removal

Tetracarboxylic acid ester was synthesized with diethyl malonate and methyl acrylate, and an amino terminated hyperbranched polymer (HBP-NH2) was prepared by reaction of a tetracarboxylic acid ester with diethylenetriamine (DETA). Hyperbranched polymer grafted chitosan (HBP-g-chitosan), a novel adsorbent material for Cr(VI) removal, was prepared from HBP-NH2 and chitosan with epichlorohydrin as crosslinking agent. The adsorbent was characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectrophotometry, and X-ray diffraction. The influence of the initial concentration of Cr(VI), the dosage of adsorbent, pH value and the coexisting anions on the adsorption performance were studied. An isotherm of the adsorption process was generated and studied by Langmuir and Freundlich models. The results showed that the Freundlich model proved to be more suitable than the Langmuir model. The adsorption kinetics were determined by pseudo-first order and pseudo-second order kinetics. In doing so, it was found that the pseudo-second order kinetic model was more reliable than the pseudo-first order kinetic model.

4-Methylbenzaldehyde thiosemicarbazone

The title compound, C9H11N3S, was prepared by reacting 4-methylbenzaldehyde with thiosemicarbazide. An intramolecular N—H⋯N hydrogen bond helps to establish the observed molecular conformation. The crystal packing is realized by intermolecular N—H⋯S hydrogen bonds.

1,2-Bis(1,3-benzothia-zol-2-yl)benzene.

The title compound, C20H12N2S2, was prepared by the reaction of o-phthalic acid and 2-aminothiophenol under microwave irradation. The phenyl ring, A, and the benzothiazolyl rings, B and C, are planar; the dihedral angles are A/B = 19.9 (11), A/C = 87.8 (3) and B/C = 84.4 (4)°. Weak intermolecular C—H⋯N hydrogen bonds link the molecule, forming zigzag chains parallel to the c axis.

Dimethyl 2,2-bis­(2-cyano­ethyl)malonate

The asymmetric unit of the title compound, C11H14N2O4, contains one half-molecule; a twofold rotation axis passes through the central C atom. Intermolecular C—H⋯N hydrogen bonds link the molecules into a one-dimensional supramolecular structure.

3,3'-Dimethyl-1,1'-[(1,3-dihy-droxy-propane-2,2-di-yl)dimethyl-idene]diimidazolium bis-(hexa-fluoro-phosphate).

The title compound, C13H22N4O2 2+·2PF6 −, was prepared by the anion exchange of the dibromide ionic liquid with potassium hexafluorophosphate. The two imidazole rings are each planar (r.m.s. deviations = 0.0016 and 0.0060 Å) and make a dihedral angle of 45.3 (18)°. Intramolecular O—H⋯F hydrogen bonds occur. Intermolecular C—H⋯F, O—H⋯O and C—H⋯O hydrogen bonds stabilize the crystal structure.

3,3-Dimethyl-1,1-(propane-1,3-di-yl)diimidazol-1-ium tetra-bromido-cadmate(II).

The title compound, (C11H18N4)[CdBr4], was prepared by an anion exchange. The dihedral angle between the two planar imidazolium rings in the cation is 74.4 (4)°. The crystal packing is stabilized by weak intermolecular C—H⋯Br hydrogen bonds between the cation and the tetrahedral anion, building up a three-dimensionnal network.

2-Bromo-1-(4-methoxy­phen­yl)ethanone

The title compound, C9H9BrO2, prepared by the reaction of 4-methoxyacetophenone and cupric bromide, , is approximately planar (r.m.s. deviation 0.0008 Å). In the crystal, weak intermolecular aromatic C—H⋯Ocarbonyl hydrogen-bonding interactions result in a one-dimensional chain structure.