scholarly journals Structural and optical properties of penicillamine-protected gold nanocluster fractions separated by sequential size-selective fractionation

2019 ◽  
Vol 10 ◽  
pp. 955-966 ◽  
Author(s):  
Xiupei Yang ◽  
Zhengli Yang ◽  
Fenglin Tang ◽  
Jing Xu ◽  
Maoxue Zhang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Quantum Confinement Effect ◽  
Water Soluble ◽  
Proton Nuclear Magnetic Resonance ◽  
Spherical Particles ◽  
Resonance Spectroscopy ◽  
Separation And Purification ◽  
Gold Nanocluster ◽  
Volume Percentage ◽  
Selective Precipitation

Polydisperse water-soluble gold nanoclusters (AuNCs) protected by penicillamine have been synthesized in this work. The sequential size-selective precipitation (SSSP) technique has been applied for the size fractionation and purification of the monolayer-protected AuNCs. Through continuously adding acetone to a crude AuNC aqueous solution and controlling the volume percentage of acetone, we successfully separated the polydisperse AuNCs with diameters ranging from 0.5 to 5.4 nm into four different fractions sequentially. High-resolution transmission electron microscopy (HRTEM) shows that the four fractions are well-dispersed spherical particles of diameter 3.0 ± 0.6, 2.3 ± 0.5, 1.7 ± 0.4, and 1.2 ± 0.4 nm. Proton nuclear magnetic resonance spectroscopy suggests that disulfide, excess ligands and gold(I) complexes were removed from the AuNCs fractions. These results demonstrate the considerable potential of the SSSP technique for size-based separation and purification of AuNCs, achieving not only the isolation of larger nanoclusters (NCs) from small NCs in a continuous fashion, but also for the removal of small-molecule impurities. Based on the results from the mass spectrometry and thermogravimetric analysis, the average composition of the four fractions can be represented by Au38(SR)18, Au28(SR)15, Au18(SR)12, and Au11(SR)8, respectively. This indicates that the SSSP separation is mainly dependent on the core size and the ratio of Au atoms to ligands of AuNCs. X-ray photoelectron spectroscopy (XPS) has also been applied to observe the molecular dependence on the gold and sulfur chemical state of organosulfur monolayers of the fractions. The photoluminescence spectra of these AuNCs in the range of 900–790 nm was investigated at room temperature. The results show that the peak emission energy of the size-selected AuNCs undergoes a blue shift when the size is decreased, which can be attributed to the quantum confinement effect.

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).

scholarly journals A molecular-level approach for characterizing water-insoluble components of ambient organic aerosol particulates using ultra-high resolution mass spectrometry

2014 ◽  
Vol 14 (7) ◽  
pp. 10393-10427
Author(s):  
A. S. Willoughby ◽  
A. S. Wozniak ◽  
P. G. Hatcher
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
High Resolution Mass Spectrometry ◽  
Organic Aerosols ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Proton Nuclear Magnetic Resonance ◽  
Aerosol Sample ◽  
Resonance Spectroscopy ◽  
Ion Cyclotron Resonance

Abstract. The chemical composition of organic aerosols in the atmosphere is strongly influenced by human emissions, and the effect these have on the environment, human health, and climate change is determined by the molecular nature of these chemical species. The complexity of organic aerosol samples limits the ability to study the chemical composition, and, therefore, the associated properties and the impacts they have. Many studies address the water-soluble fraction of organic aerosols, and have had much success in identifying specific molecular formulas for thousands of compounds present. However, little attention is given to the water-insoluble portion, which can contain most of the fossil material that is emitted through human activity. Here we compare the organic aerosols present in water extracts and organic solvent extracts (pyridine and acetonitrile) of an ambient aerosol sample collected in a rural location that is impacted by natural and anthropogenic emission sources. A semi-quantitative method was developed using proton nuclear magnetic resonance spectroscopy to determine that the amount of organic matter extracted by pyridine is comparable to that of water. Electrospray ionization Fourier transform ion cyclotron resonance mass spectra show that pyridine extracts a molecularly unique fraction of organic matter compared to water or acetonitrile, which extract chemically similar organic matter components. The molecular formulas unique to pyridine were less polar, more aliphatic, and reveal formulas containing sulfur to be an important component of insoluble aerosol organic matter.

A novel and highly efficient polymerization of sulfomethylated alkaline lignins via alkyl chain cross-linking method

Holzforschung ◽  
2016 ◽  
Vol 70 (4) ◽  
pp. 297-304 ◽  
Author(s):  
Nanlong Hong ◽  
Wei Yu ◽  
Yuyuan Xue ◽  
Weimei Zeng ◽  
Jinhao Huang ◽  
...  
Keyword(s):  
Group Analysis ◽  
Gel Permeation Chromatography ◽  
Water Soluble ◽  
Raw Material ◽  
Low Rank ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
One Pot ◽  
New Family ◽  
High Degree

Abstract A new family of water-soluble lignosulfonate polymers with ultrahigh molecular weight (Mw) was developed based on alkali lignin (AL) as starting material in a one-pot reaction in two steps: sulfomethylation of AL as raw material led to AL-S and this material was subsequently cross-linked via alkylation with 1,6-dibromohexane (alkAL-S). Gel permeation chromatography showed a significant increase of Mw from 5200 Da of AL-S to 201 000 Da of alkAL-S with high degree of alkylation. Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy and functional group analysis confirmed the efficient polymerization by a nucleophilic substitution reaction mechanism. Additionally, alkAL-S with high Mw showed unexpected viscosity-reducing effect, stability and good rheological properties on a low-rank coal-water slurry (CWS), which are even better than those obtained by naphthalene sulfonate formaldehyde (NSF) as additive. The adsorption properties of the new products were also characterized via a quartz crystal microbalance combined with dissipation monitoring (QCM-D method). Cross-linked structure, large steric hindrance from high Mw and suitable amphiphilic properties of alkAL-S polymers contribute together to the highly improved dispersion performances for CWS.

scholarly journals Chemical composition, optical properties, and oxidative potential of water- and methanol-soluble organic compounds emitted from the combustion of biomass materials and coal

2021 ◽  
Author(s):  
Tao Cao ◽  
Meiju Li ◽  
Chunlin Zou ◽  
Xingjun Fan ◽  
Jianzhong Song ◽  
...  
Keyword(s):  
Optical Properties ◽  
Organic Compounds ◽  
1H Nmr ◽  
Water Soluble ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Oxidative Potential ◽  
Strong Light ◽  
Chemical Structures ◽  
Biomass Materials

Abstract. Biomass burning (BB) and coal combustion (CC) are important sources of brown carbon (BrC) in ambient aerosols. In this study, six biomass materials and five types of coal were combusted to generate fine smoke particles. The BrC fractions, including water-soluble organic compounds (WSOC), humic-like substances (HULIS), and methanol-soluble organic compounds (MSOC), were subsequently fractionated and their optical properties and chemical structures were then comprehensively investigated using UV-visible spectroscopy, proton nuclear magnetic resonance spectroscopy (1H-NMR), and fluorescence extraction-emission matrix spectroscopy (EEM) combined with parallel factor analysis (PARAFAC). In addition, the oxidative potential (OP) of BB and CC BrC was measured with the dithiothreitol (DTT) method. The results showed that WSOC, HULIS, and MSOC accounted for 2.3 %–22 %, 0.5 %–10 %, and 6.4 %–73 % of the total mass of combustion-derived PM2.5, respectively, with MSOC extracting the highest concentrations of organic compounds. The MSOC fractions had the highest light absorption capacity (mass absorption efficiency at 365 nm (MAE365): 1.0–2.7 m2/gC) for both BB and CC smoke, indicating that MSOC contained more of the strong light-absorbing components. Therefore, MSOC may better represent the total BrC than the water-soluble fractions. Some significant differences were observed between the BrC fractions emitted from BB and CC, with more water-soluble BrC fractions with higher MAE365 and lower absorption Ångström exponent values detected in smoke emitted from BB than from CC. The EEM-PARAFAC analysis identified four fluorophores: two protein-like, one humic-like, and one polyphenol-like. The protein-like substance was the dominant component of WSOC (47 %–80 %), HULIS (44 %–87 %), and MSOC (42 %–70 %). The 1H-NMR results suggested that BB BrC contained more oxygenated aliphatic functional groups (H-C-O), whereas CC BrC contained more unsaturated fractions (H-C-C = and Ar-H). The DTT assays indicated that BB BrC generally had a stronger OP (DTTmass, 2.6–85 pmol/min/μg) than CC BrC (DTTmass, 0.4–11 pmol/min/μg), with MSOC having a stronger OP than WSOC and HULIS. Therefore, the BrC fractions from BB had higher OP values than those from CC.

scholarly journals A molecular-level approach for characterizing water-insoluble components of ambient organic aerosol particulates using ultrahigh-resolution mass spectrometry

2014 ◽  
Vol 14 (18) ◽  
pp. 10299-10314 ◽  
Author(s):  
A. S. Willoughby ◽  
A. S. Wozniak ◽  
P. G. Hatcher
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
Organic Aerosols ◽  
Chemical Species ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Proton Nuclear Magnetic Resonance ◽  
Aerosol Sample ◽  
Resonance Spectroscopy ◽  
Ion Cyclotron Resonance

Abstract. The chemical composition of organic aerosols in the atmosphere is strongly influenced by human emissions. The effect these have on the environment, human health, and climate change is determined by the molecular nature of these chemical species. The complexity of organic aerosol samples limits the ability to study the chemical composition, and therefore the associated properties and the impacts they have. Many studies have addressed the water-soluble fraction of organic aerosols and have had much success in identifying specific molecular formulas for thousands of compounds present. However, little attention is given to the water-insoluble portion, which can contain most of the fossil material that is emitted through human activity. Here we compare the organic aerosols present in water extracts and organic solvent extracts (pyridine and acetonitrile) of an ambient aerosol sample collected in a rural location that is impacted by natural and anthropogenic emission sources. A semiquantitative method was developed using proton nuclear magnetic resonance spectroscopy to determine that the amount of organic matter extracted by pyridine is comparable to that of water. Electrospray ionization Fourier transform ion cyclotron resonance mass spectra show that pyridine extracts a molecularly unique fraction of organic matter compared to water or acetonitrile, which extract chemically similar organic matter components. The molecular formulas unique to pyridine were less polar, more aliphatic, and reveal formulas containing sulfur to be an important component of insoluble aerosol organic matter.

Preparation and characterisation of water soluble polyester coatings based on waste materials

2017 ◽  
Vol 46 (5) ◽  
pp. 408-422 ◽  
Author(s):  
Soheir Youssef Tawfik ◽  
Magdy Wadid Sabaa ◽  
Ramzy Takawy Botros
Keyword(s):  
Value Added ◽  
Environmentally Friendly ◽  
Water Soluble ◽  
Raw Material ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Waste Products ◽  
Pet Waste ◽  
Content Type

Purpose The purpose of this paper is to prepare cheap and environmentally friendly water soluble polyester coatings through the glycolysis of poly(ethylene terephthalate) (PET) waste. Design/methodology/approach A secondary value-added polyester coatings were prepared from PET waste. The first step was the de-polymerisation of PET waste by 2,2-dimethyl-1,3-propanediol with different molar ratios in the presence of different concentrations of zinc acetate as trans-esterification catalyst. The de-polymerised product was characterised by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1HNMR), differential scanning calorimetry and hydroxyl values. The polyesters were successfully synthesised by esterification of the glycolysed product with adipic acid, isophthalic acid, 2,2-dimethyl-1,3-propanediol and trimellitic anhydride in different ratios. FTIR and 1HNMR were used qualitatively and quantitatively to elucidate the structure of the prepared polyesters. Hydroxyl value and the physical properties of the prepared polyesters were also investigated. Two different curing agents were used to prepare the coatings based on the prepared polyesters. Findings Useful coating products were obtained by chemical (glycolysis) of post consumed PET wastes. The 2,2-dimethyl-1,3-propanediol was found to be good glycol in the glycolysis of PET. It was noticed that the rate of glycolysis increases with increasing the amount of catalyst, time of glycolysis and amount of 2,2-dimethyl-1,3-propanediol. N,N-Dimethylethanol amine was a good neutralising agent used for the preparation of water soluble coatings based on glycolysed product of PET. Practical implications The use of waste products like PET waste in water soluble coating systems will bring down the costs of the coatings and will also open a new market of recycled plastic materials and, hence, may provide a potential solution to the problems of solid waste management. It is an attractive option for environmentally friendly and efficient disposal of plastic waste. Originality/value The paper provides a potential way to use undesirable PET waste as industrial raw material. The coatings prepared are eco-friendly, soluble in water that can replace other expensive polyester coatings that are soluble in organic solvents and not environmentally coatings.

Use of thioglycerol on porous polyurethane as an effective theranostic capping agent for bone tissue engineering

2018 ◽  
Vol 33 (7) ◽  
pp. 955-966 ◽  
Author(s):  
Eun-Ho Song ◽  
Yun-Jeong Seong ◽  
Cheonil Park ◽  
In-Gu Kang ◽  
Hyoun-Ee Kim ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
In Vitro Release ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Prolonged Release ◽  
One Pot ◽  
Conjugate System ◽  
Covalently Linked

Thiolated biodegradable polyurethane (TG-DPU) was synthesized using a one-pot reaction with thioglycerol adopted as a functionalized chain extender. After characterization of the chemical structure of TG-DPU using proton nuclear magnetic resonance spectroscopy, bone morphogenetic protein (BMP-2) was loaded in the TG-DPU under oxidative conditions to form disulfides between the free thiol of TG-DPU and BMP-2. The interaction between TG-DPU and BMP-2, so-called bioconjugates, was investigated using X-ray photoelectron spectroscopy analysis; the appearance of disulfide (S–S) linkage indicated the formation of a polymer/growth factor conjugate system. The covalently linked bioconjugates provided stability with minimal loss during the drug delivery with prolonged release performance in in vitro release tests. The effects of the drugs delivered by TG-DPU were also confirmed by in vitro alkaline phosphatase tests using pre-osteoblasts and in vivo bone regeneration tests. The drugs effectively induced cell differentiation and promoted mature bone recovery.

Synthesis and Characterization of Fluorescent Acrylamide Water Soluble Macromer

2012 ◽  
Vol 488-489 ◽  
pp. 216-220
Author(s):  
Datchanee Kraisiri ◽  
Nuanphun Chantarasiri ◽  
Vimolvan Pimpan
Keyword(s):  
Chemical Structure ◽  
Continuous Phase ◽  
Water Soluble ◽  
Proton Nuclear Magnetic Resonance ◽  
Synthesis And Characterization ◽  
Resonance Spectroscopy ◽  
Visible Absorption ◽  
Emulsifier System ◽  
Polymerization Method

Fluorescent acrylamide water soluble macromer was synthesized from dimethylaminopropylmethacrylamide-9-(chloromethyl)anthracene quaternary ammonium salt monomer using an inverse emulsion polymerization method. It was initiated by benzoylperoxide and stabilized by a co-emulsifier system consisting of Span®80 and Tween®60 dispersed in a continuous phase of cyclohexane with HLB value of 6.42. The polymerization was done at 80°C for 4 hours. The obtained macromer exhibited similar functional groups, ultraviolet-visible absorption and fluorescent emission but different solubility when compared to the monomer. Further analyses by proton nuclear magnetic resonance spectroscopy and mass spectrometry revealed the chemical structure of the macromer as a dimer of the monomer containing carcon-carbon double bonds.

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