scholarly journals Recoverable Water-soluble Polyethylene Glycol-immobilized N-hydroxyphthalimide Mediated Oxidation of Cellulose in the Presence of NaBr and NaClO

2021 ◽  
Author(s):  
Huimin Wang ◽  
Xiaoying Wang ◽  
Tingting Sun ◽  
Peixin Li ◽  
Xiaomeng Chu ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Water Solubility ◽  
Cellulose Degradation ◽  
Catalytic Performance ◽  
Water Soluble ◽  
Resonance Spectroscopy ◽  
Oxidized Cellulose ◽  
Carboxyl Content ◽  
Selective Catalytic Oxidation ◽  
Mediated Oxidation

Abstract As a highly efficient nitroxide radical catalyst for selective catalytic oxidation of cellulose, N-hydroxyphthalimide (NHPI) has attracted much attention because of its low price and light cellulose degradation. However, NHPI is insoluble in water and is difficult to recycle because of its small molecular weight. To address the above issues, the water-soluble polyethylene glycol (PEG)-immobilized NHPI catalyst (PEG-NHPI) was designed and prepared in this work. Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC) and UV-vis light spectroscopy were used to characterize PEG-NHPI. The results showed that PEG-NHPI catalysts with good water solubility and adjustable NHPI loading amounts were successfully synthesized. Using NaBr as promoter and NaClO as oxidant, PEG-NHPI mediated oxidation of cellulose was carried out and good catalytic performance was found. The catalytic performance of PEG-NHPI mediated oxidation of cellulose in water was higher than that in acetonitrile-water. The carboxyl content of PEG-NHPI oxidized cellulose could reach the level of free NHPI oxidized cellulose, and was equivalent to 68% of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) oxidized cellulose, while the degradation degree of cellulose was greatly reduced by more than 40%. The catalytic performance did not decrease significantly after six oxidation cycles. The structure of recycled PEG-NHPI was not changed. These results indicated that immobilizing NHPI onto PEG can achieve the unification of high catalytic performance and good recyclability.

scholarly journals Recoverable acrylamide-vinylamine copolymer immobilized TEMPO mediated oxidation of cellulose with good catalytic performance and low cellulose degradation

2021 ◽  
Author(s):  
Tingting Sun ◽  
Huimin Wang ◽  
Jiaye Liu ◽  
Xiaomeng Chu ◽  
Xuteng Xing ◽  
...  
Keyword(s):  
Selective Oxidation ◽  
Cellulose Degradation ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
Hydroxyl Groups ◽  
Oxidized Cellulose ◽  
Carboxyl Content ◽  
Amine Groups ◽  
Degradation Degree ◽  
Mediated Oxidation

Abstract In this work, a recoverable acrylamide-vinylamine copolymer immobilized TEMPO (P(AM-co-VAm)-T) catalyst for selective oxidation of cellulose with good catalytic performance and low cellulose degradation was developed. Firstly, the acrylamide-vinylamine copolymer (P(AM-co-VAm)) was prepared by Hofmann degradation of polyacrylamide (PAM). Then, the condensation reduction reaction between amine groups of P(AM-co-VAm) and carbonyl groups of 4-oxo-TEMPO yielded P(AM-co-VAm)-T. P(AM-co-VAm)-T was used as a catalyst for selective oxidation of C6 primary hydroxyl groups of cellulose to carboxyl groups. The carboxyl content of obtained oxidized cellulose was up to 1.114 mmol/g, which was equivalent to 76% of the free TEMPO level. This macromolecular catalyst was easily recycled and the recycling performance was excellent. Interestingly, it was found that P(AM-co-VAm)-T could effectively reduce the degradation of oxidized cellulose. The corresponding degradation degree was 21%-27%, which was much lower than the degradation degree of free TEMPO (61%-66%) and other macromolecular TEMPO catalysts, such as polyacrylic acid immobilized-TEMPO (41%-53%) and polyamidoamine supported TEMPO (28%-44%). P(AM-co-VAm)-T with positive charge and suitable size could effectively inhibit the formation of C6 aldehydes and C2/C3 ketones, which was the main reason that it could significantly inhibit cellulose degradation.

scholarly journals Effect of DMPA and Molecular Weight of Polyethylene Glycol on Water-Soluble Polyurethane

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1915 ◽  
Author(s):  
Eyob Wondu ◽  
Hyun Woo Oh ◽  
Jooheon Kim
Keyword(s):  
Molecular Weight ◽  
Contact Angle ◽  
Polyethylene Glycol ◽  
Photoelectron Spectroscopy ◽  
Water Solubility ◽  
Soft Segment ◽  
Water Soluble ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry

In this study water-soluble polyurethane (WSPU) was synthesized from isophorone diisocyanate (IPDI), and polyethylene glycol (PEG), 2-bis(hydroxymethyl) propionic acid or dimethylolpropionic acid (DMPA), butane-1,4-diol (BD), and triethylamine (TEA) using an acetone process. The water solubility was investigated by solubilizing the polymer in water and measuring the contact angle and the results indicated that water solubility and contact angle tendency were increased as the molecular weight of the soft segment decreased, the amount of emulsifier was increased, and soft segment to hard segment ratio was lower. The contact angle of samples without emulsifier was greater than 87°, while that of with emulsifier was less than 67°, indicating a shift from highly hydrophobic to hydrophilic. The WSPU was also analyzed using Fourier transform infrared spectroscopy (FT-IR) to identify the absorption of functional groups and further checked by X-ray photoelectron spectroscopy (XPS). The molecular weight of WSPU was measured using size-exclusion chromatography (SEC). The structure of the WSPU was confirmed by nuclear magnetic resonance spectroscopy (NMR). The thermal properties of WSPU were analyzed using thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC).

Water soluble multiarm-polyethylene glycol–betulinic acid prodrugs: design, synthesis, and in vivo effectiveness

2014 ◽  
Vol 5 (19) ◽  
pp. 5775-5783 ◽  
Author(s):  
Lin Dai ◽  
Dan Li ◽  
Jing Cheng ◽  
Jing Liu ◽  
Li-Hong Deng ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Betulinic Acid ◽  
Water Solubility ◽  
Drug Loading ◽  
Water Soluble ◽  
Loading Capacity ◽  
Design Synthesis ◽  
High Drug ◽  
High Drug Loading

Multiarm-polyethylene glycol–betulinic acid prodrugs were prepared by using multiarm-polyethylene glycol linkers and betulinic acid, which exhibited high drug loading capacity, good water solubility, and excellent anticancer activity.

IMPROVEMENT OF WATER SOLUBILITY AND IN VITRO DISSOLUTION RATE OF DEFLAZACORT BY COMPLEXATION WITH Β-CYCLODEXTRIN THROUGH FREEZE DRYING PROCESS

INDIAN DRUGS ◽  
2020 ◽  
Vol 57 (07) ◽  
pp. 70-73
Author(s):  
Nilesh S Kulkarni ◽  
Pallavi D Gitte ◽  
Manojkumar K Munde ◽  
Shashikant N. Dhole
Keyword(s):  
Dissolution Rate ◽  
Freeze Drying ◽  
Water Solubility ◽  
Water Soluble ◽  
In Vitro Dissolution ◽  
Resonance Spectroscopy ◽  
Cyclodextrin Complex ◽  
Water Soluble Polymer ◽  
Freeze Dried

Deflazacort is a poorly water-soluble drug and is practically insoluble in water. The objective of this study was to improve the solubility of deflazacort by using as solubility enhancer β-cyclodextrin and also to study the effect of the water-soluble polymer PEG 4000 on solubility of the deflazacort:β-cyclodextrin binary system. The inclusion complexes of deflazacort with β-cyclodextrin in 1:1 w/w, 1:2 w/w and 1:3 w/w proportions were prepared by kneading, microwave irradiation and freeze-drying techniques. The in vitro dissolution study showed improved dissolution rate for deflazacort for freeze-dried binary deflazacort: β-cyclodextrin 1:2 w/w complex, as compared to ternary deflazacort:β-cyclodextrin: PEG 6000 1:2 w/w complexes, plain deflazacort, physical mixtures and complexes prepared by kneading and microwave technique. This was confirmed by Fourier transform infrared spectroscopy, differential scanning calorimetry, powder x-ray diffraction study, scanning electron microscopy and 1 H nuclear magnetic resonance spectroscopy study. Thus, deflazacort:β-cyclodextrin complex with improved solubility was successfully developed using freeze drying technique.

TEMPO-mediated oxidation of softwood thermomechanical pulp

Holzforschung ◽  
2009 ◽  
Vol 63 (5) ◽  
Author(s):  
Yusuke Okita ◽  
Tsuguyuki Saito ◽  
Akira Isogai
Keyword(s):  
Sodium Hypochlorite ◽  
Cellulose Nanofibers ◽  
Water Soluble ◽  
Sodium Bromide ◽  
Thermomechanical Pulp ◽  
Oxidized Cellulose ◽  
Sugar Composition ◽  
Cellulose I ◽  
Mediated Oxidation ◽  
Soluble Fractions

Abstract A softwood thermomechanical pulp (TMP) was suspended in water and oxidized with sodium hypochlorite and catalytic amounts of sodium bromide and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) at pH 10. When the NaClO addition levels were 20–26 mmol g-1 of the TMP, the yields of water-insoluble TEMPO-oxidized TMPs fractions were approximately 40%. Sugar composition and other analyses revealed that most of the lignin and hemicellulose components in the TMP were removed as water-soluble fractions by the oxidation. Thus, almost pure TEMPO-oxidized celluloses can also be prepared from TMP, although the addition levels of NaClO are much higher than for the TEMPO-mediated oxidation of pure celluloses. The water-soluble fractions were analyzed by NMR, showing that polyuronic acids formed from glucomannan and cellulose by oxidation were the main compounds. The water-insoluble fractions of TEMPO-oxidized TMPs prepared with NaClO of 20–26 mmol g-1 had carboxylate contents of approximately 1.2 mmol g-1, and had the same cellulose I allomorph and the same crystal widths as in the original TMP. Transparent and highly viscous gels were obtained by disintegration of these TEMPO-oxidized TMPs in water, and the gels consisted of individual nanofibers 4–6 nm in width. Thus, TEMPO-oxidized cellulose nanofibers can also be prepared from TMP.

Study on Elimination of Surface-Exfoliation and Crack of ZrO2 Green Body of Gelcasting with Water-Solubility Macromolecule

2005 ◽  
Vol 475-479 ◽  
pp. 1317-1320
Author(s):  
Zhong Zhou Yi ◽  
Shi-en Wang ◽  
Yong Huang
Keyword(s):  
Polyethylene Glycol ◽  
Flexural Strength ◽  
Rheological Property ◽  
Water Solubility ◽  
Water Soluble ◽  
The Other ◽  
Green Body ◽  
Water Soluble Polymer ◽  
Gelation Behavior ◽  
New System

Ceramic gelcasting has to be performed in nitrogen to avoid surface-exfoliation and crack of the green body. The rapid drying of gelled bodies can cause nonuniform shrinkage. Non-uniform drying in various regions due to the solvent gradient, induces structural and residual stresses which cause defects, such as cracking, warpage and the other malformations. These malformations can be minimized or eliminated via adding a proper amount of water-soluble polymer polyethylene glycol(PEG).This study concentrates attention on dispersion, rheological property and gelation behavior in the new system, The flexural strength and microstructure of ZrO2 green bodies were measured and observed.

BODIPY Fluorophores for Membrane Potential Imaging

2019 ◽  
Author(s):  
Jenna Franke ◽  
Benjamin Raliski ◽  
Steven Boggess ◽  
Divya Natesan ◽  
Evan Koretsky ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Water Solubility ◽  
Water Soluble ◽  
Voltage Sensitivity ◽  
Chemical Transformations ◽  
Direct Modification ◽  
Biological Compatibility ◽  
Meso Position ◽  
Ionizable Groups ◽  
Boron Center

Fluorophores based on the BODIPY scaffold are prized for their tunable excitation and emission profiles, mild syntheses, and biological compatibility. Improving the water-solubility of BODIPY dyes remains an outstanding challenge. The development of water-soluble BODIPY dyes usually involves direct modification of the BODIPY fluorophore core with ionizable groups or substitution at the boron center. While these strategies are effective for the generation of water-soluble fluorophores, they are challenging to implement when developing BODIPY-based indicators: direct modification of BODIPY core can disrupt the electronics of the dye, complicating the design of functional indicators; and substitution at the boron center often renders the resultant BODIPY incompatible with the chemical transformations required to generate fluorescent sensors. In this study, we show that BODIPYs bearing a sulfonated aromatic group at the meso position provide a general solution for water-soluble BODIPYs. We outline the route to a suite of 5 new sulfonated BODIPYs with 2,6-disubstitution patterns spanning a range of electron-donating and -withdrawing propensities. To highlight the utility of these new, sulfonated BODIPYs, we further functionalize them to access 13 new, BODIPY-based voltage-sensitive fluorophores. The most sensitive of these BODIPY VF dyes displays a 48% ΔF/F per 100 mV in mammalian cells. Two additional BODIPY VFs show good voltage sensitivity (≥24% ΔF/F) and excellent brightness in cells. These compounds can report on action potential dynamics in both mammalian neurons and human stem cell-derived cardiomyocytes. Accessing a range of substituents in the context of a water soluble BODIPY fluorophore provides opportunities to tune the electronic properties of water-soluble BODIPY dyes for functional indicators.

Structure of a shear-thickening polysaccharide extracted from the New Zealand black tree fern, Cyathea medullaris

2020 ◽  
Author(s):  
M Wee ◽  
M Mastrangelo ◽  
Susan Carnachan ◽  
Ian Sims ◽  
K Goh
Keyword(s):  
New Zealand ◽  
Uronic Acid ◽  
Average Molecular Weight ◽  
Shear Thickening ◽  
Water Soluble ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Tree Fern ◽  
13C Nuclear Magnetic Resonance ◽  
Exclusion Chromatography

A shear-thickening water-soluble polysaccharide was purified from mucilage extracted from the fronds of the New Zealand black tree fern (Cyathea medullaris or 'mamaku' in Māori) and its structure characterised. Constituent sugar analysis by three complementary methods, combined with linkage analysis (of carboxyl reduced samples) and 1H and 13C nuclear magnetic resonance spectroscopy (NMR) revealed a glucuronomannan comprising a backbone of 4-linked methylesterified glucopyranosyl uronic acid and 2-linked mannopyranosyl residues, branched at O-3 of 45% and at both O-3 and O-4 of 53% of the mannopyranosyl residues with side chains likely comprising terminal xylopyranosyl, terminal galactopyranosyl, non-methylesterified terminal glucopyranosyl uronic acid and 3-linked glucopyranosyl uronic acid residues. The weight-average molecular weight of the purified polysaccharide was ~1.9×106Da as determined by size-exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS). The distinctive rheological properties of this polysaccharide are discussed in relation to its structure. © 2014 Elsevier B.V.

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