Rheological Properties of Associative Polyelectrolytes Synthesized by Solution Polymerization

2014 ◽  
Vol 1613 ◽  
pp. 151-156
Author(s):  
Areli I. Velazquez ◽  
Alejandro Coronado ◽  
Enrique J. Jiménez
Keyword(s):  
Ethyl Acrylate ◽  
Molecular Structures ◽  
Water Soluble ◽  
Molar Ratio ◽  
Solution Polymerization ◽  
Polymer Microstructure ◽  
Hydrophobically Modified ◽  
Linear Viscoelastic ◽  
Combined Structure ◽  
Thickening Power

ABSTRACTWater-soluble associative polyelectrolytes of methacrylic acid [MAA] and ethyl acrylate [EA] (1:1 molar ratio), hydrophobically modified with small amounts of stearyl metacrylate [MM18], were synthesized by means of solution polymerization. Polyelectrolytes with two different molecular structures: multisticker, with hydrophobic groups randomly distributed along the hydrophilic chain and combined, with the hydrophobic groups along the chain and as terminal groups of the backbone, were obtained. Steady shear behavior and linear viscoelastic properties were studied as a function of polymer microstructure and hydrophobic group concentrations on salt-free aqueous solution using a cone-and-plate rheometer. Concentration regimes were obtained for each synthetized polymer. Viscoelastic study shows that the maximum thickening effect corresponds to the combined structure followed by multisticker structure. These polyelectrolytes exhibit high thickening power on aqueous solutions due to the synergy between the hydrophobic attractive interactions and coil expansion phenomena.

Solubility Enhancement of the Poorly Water-Soluble Antiulcer Drug Famotidine by Inclusion Complexation

2013 ◽  
Vol 6 (1) ◽  
pp. 1983-1989 ◽  
Author(s):  
Shabnam Ain ◽  
V Gupta ◽  
Babita K ◽  
Q Ain ◽  
J Dahiya
Keyword(s):  
Inclusion Complex ◽  
Dissolution Rate ◽  
Phosphate Buffer ◽  
Physical Mixture ◽  
Water Soluble ◽  
Molar Ratio ◽  
Phase Solubility ◽  
Distilled Water ◽  
Physicochemical Interaction ◽  
Mixture Phase

Aqueous solubility is a critical factor for optimum drug delivery. In the present study, we investigated the potential of drug-cyclodextrin complexation as an approach for improving the solubility and bioavailability of famotidine, an H2-receptor antagonist and acid reducing drug which has poor solubility and bioavailability. Solubility improvement of drug by β-cyclodextrin was done by simple complexation approach using physical, kneading and co-precipitation methods and compared with physical mixture. Phase solubility profile indicated that the solubility of famotidine was significantly increased in presence of β-cyclodextrin and shows a linear graph with β-cyclodextrin indicating formation of inclusion complexes in a 1:1 molar ratio. β-Cyclodextrin-famotidine mixture have maximum stability constant 1477.6 M-1. The inclusion complex ratio 1:1 of kneading mixture was selected based on drug release profile and compared with physical mixture. Further characterization was done by  using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) to identify the physicochemical interaction between drug and carrier and its effect on dissolution. Dissolution rate studies for selected inclusion complex was performed in 0.1 N HCl (pH 1.2), phosphate buffer (pH 7.5) and distilled water (pH 6.8) and compared these to pure drug profile which was found to be 2.34 fold increase in distilled water, 1.83 fold in HCl and 2.01 fold in phosphate buffer (pH 7.5). These results suggest that the kneaded complex of famotidine with β-cyclodextrin as hydrophilic complexation agent can substantially enhance the solubility and dissolution rate. Such complex has promising potential to improve the bioavailability of famotidine.  

A Solvent-Dependent and Electrochemically Controlled Self-Assembling/Disassembling System

2003 ◽  
Vol 68 (9) ◽  
pp. 1647-1662 ◽  
Author(s):  
Valeria Amendola ◽  
Massimo Boiocchi ◽  
Yuri Diaz Fernandez ◽  
Carlo Mangano ◽  
Piersandro Pallavicini
Keyword(s):  
Equilibrium Mixture ◽  
Bidentate Ligand ◽  
Molecular Structures ◽  
The Self ◽  
Molar Ratio ◽  
Crystal And Molecular Structures ◽  
Self Assembling ◽  
Irreversible Oxidation ◽  
Irreversible Reduction ◽  
Metal Ligand

The bis-bidentate ligand R,S-1,2-diphenyl-N,N'-bis(2-quinolinemethylidene)ethane-1,2-diamine (ligand 4), containing two (iminomethyl)quinoline moieties separated by a cis-1,2-diphenylethylene spacer, forms stable complexes with both CuI and CuII. With CuII, the monomeric 1:1 complex [CuII(4)]2+ is obtained both in CH3CN and CH2Cl2. With CuI and overall 1:1 metal/ligand molar ratio, an equilibrium mixture is obtained in CH3CN, consisting of [CuI(4)2]+, [CuI2(4)2]2+ and [CuI2(4)(CH3CN)4]2+. The preponderant species is the two-metal one-ligand "open" complex [CuI2(4)(CH3CN)4]2+, in which each Cu+ cation is coordinated in a tetrahedral fashion by one (iminomethyl)quinoline unit and by two CH3CN molecules. Precipitation from the equilibrium mixture yields only crystals of [CuI2(4)(CH3CN)4](ClO4)2·2CH3CN, whose crystal and molecular structures have been determined. On the other hand, in the poorly coordinating CH2Cl2 solvent, only the dimeric helical [CuI2(4)2]2+ complex is obtained, when the overall metal/ligand 1:1 molar ratio is chosen. Addition of large quantities of acetonitrile to solutions of [CuI2(4)2]2+ in dichlorometane results in the formation of [CuI2(4)(CH3CN)4]2+, i.e. in the solvent-driven disassembling of the CuI helicate. While electrochemistry in CH3CN is poorly defined due to the presence of more than one CuI species, cyclic voltammetry experiments carried out in CH2Cl2 revealed a well defined behavior, with irreversible oxidation of [CuI2(4)2]2+ and irreversible reduction of [CuII(4)]2+ taking place at separate potentials (∆E ≈ 700 mV). Irreversibility and separation of the redox events are due to the self-assembling and disassembling processes following the reduction and oxidation, respectively.

Enhancement of the Solubility and Efficacy of Poorly Water-Soluble Drugs by Hydrophobically-Modified Polysaccharide Derivatives

2007 ◽  
Vol 24 (12) ◽  
pp. 2317-2326 ◽  
Author(s):  
Widad Henni-Silhadi ◽  
Michel Deyme ◽  
Marie-Martine Boissonnade ◽  
Martine Appel ◽  
Didier Le Cerf ◽  
...  
Keyword(s):  
Water Soluble ◽  
Poorly Water Soluble Drugs ◽  
Hydrophobically Modified ◽  
Water Soluble Drugs ◽  
Poorly Water Soluble ◽  
Polysaccharide Derivatives

scholarly journals Comprehensive characterization of humic-like substances in smoke PM<sub>2.5</sub> emitted from the combustion of biomass materials and fossil fuels

2016 ◽  
Vol 16 (20) ◽  
pp. 13321-13340 ◽  
Author(s):  
Xingjun Fan ◽  
Siye Wei ◽  
Mengbo Zhu ◽  
Jianzhong Song ◽  
Ping'an Peng
Keyword(s):  
Coal Combustion ◽  
Fossil Fuels ◽  
Solid Phase ◽  
Water Soluble ◽  
Total Carbon ◽  
Atmospheric Environment ◽  
Molar Ratio ◽  
Resonance Spectroscopy ◽  
Molar Ratios ◽  
Biomass Materials

Abstract. Humic-like substances (HULIS) in smoke fine particulate matter (PM2.5) emitted from the combustion of biomass materials (rice straw, corn straw, and pine branch) and fossil fuels (lignite coal and diesel fuel) were comprehensively studied in this work. The HULIS fractions were first isolated with a one-step solid-phase extraction method, and were then investigated with a series of analytical techniques: elemental analysis, total organic carbon analysis, UV–vis (ultraviolet–visible) spectroscopy, excitation–emission matrix (EEM) fluorescence spectroscopy, Fourier transform infrared spectroscopy, and 1H-nuclear magnetic resonance spectroscopy. The results show that HULIS account for 11.2–23.4 and 5.3 % of PM2.5 emitted from biomass burning (BB) and coal combustion, respectively. In addition, contributions of HULIS-C to total carbon and water-soluble carbon in smoke PM2.5 emitted from BB are 8.0–21.7 and 56.9–66.1 %, respectively. The corresponding contributions in smoke PM2.5 from coal combustion are 5.2 and 45.5 %, respectively. These results suggest that BB and coal combustion are both important sources of HULIS in atmospheric aerosols. However, HULIS in diesel soot only accounted for  ∼  0.8 % of the soot particles, suggesting that vehicular exhaust may not be a significant primary source of HULIS. Primary HULIS and atmospheric HULIS display many similar chemical characteristics, as indicated by the instrumental analytical characterization, while some distinct features were also apparent. A high spectral absorbance in the UV–vis spectra, a distinct band at λex∕λem ≈  280∕350 nm in EEM spectra, lower H ∕ C and O ∕ C molar ratios, and a high content of [Ar–H] were observed for primary HULIS. These results suggest that primary HULIS contain more aromatic structures, and have a lower content of aliphatic and oxygen-containing groups than atmospheric HULIS. Among the four primary sources of HULIS, HULIS from BB had the highest O ∕ C molar ratios (0.43–0.54) and [H–C–O] content (10–19 %), indicating that HULIS from this source mainly consisted of carbohydrate- and phenolic-like structures. HULIS from coal combustion had a lower O ∕ C molar ratio (0.27) and a higher content of [Ar–H] (31 %), suggesting that aromatic compounds were extremely abundant in HULIS from this source. Moreover, the absorption Ångström exponents of primary HULIS from BB and coal combustion were 6.7–8.2 and 13.6, respectively. The mass absorption efficiencies of primary HULIS from BB and coal combustion at 365 nm (MAE365) were 0.97–2.09 and 0.63 m2 gC−1, respectively. Noticeably higher MAE365 values for primary HULIS from BB than coal combustion indicate that the former has a stronger contribution to the light-absorbing properties of aerosols in the atmospheric environment.

Flow of Hydrophobically Modified Water-Soluble-Polymer Solutions in Porous Media: New Experimental Insights in the Diluted Regime

SPE Journal ◽  
2010 ◽  
Vol 16 (01) ◽  
pp. 43-54 ◽  
Author(s):  
Guillaume Dupuis ◽  
David Rousseau ◽  
René Tabary ◽  
Bruno Grassl
Keyword(s):  
Oil Recovery ◽  
Polymer Concentration ◽  
Adsorbed Layer ◽  
Water Soluble ◽  
Water Soluble Polymer ◽  
Improved Oil Recovery ◽  
Water Soluble Polymers ◽  
Resistance Factors ◽  
Soluble Polymers ◽  
Hydrophobically Modified

Summary The specific molecular structure of hydrophobically modified water-soluble polymers (HMWSPs), also called hydrophobically associative polymers, gives them interesting thickening and surface-adsorption abilities compared with classical water-soluble polymers (WSPs), which could be useful in polymer-flooding and well-treatment operations. However, their strong adsorption obviously can impair their injectivity, and, conversely, the shear sensitivity of their gels can be detrimental to well treatments. Determining for which improved-oil-recovery (IOR) application HMWSPs are best suited, therefore, remains difficult. The aim of this work is to bring new insight regarding the interaction mechanisms between HMWSPs and rock matrix and the consequences concerning their propagation in reservoirs. A consistent set of HMWSPs with sulfonated polyacrylamide backbones and alkyl hydrophobic side chains together with an equivalent WSP was synthesized and fully characterized. HMWSP and WSP solutions were then injected in model granular packs. As expected, with HMWSPs, high resistance factors (or mobility reductions, Rm) were observed. Yet, within the limit of the injected volumes, the effluent showed the same viscosity and polymer concentration as the injected solutions. A first significant outcome concerns the specificities of the Rm curves during HMWSP injections. Rm increases took place in two steps. The first corresponded to the propagation of the viscous front, as observed with WSP, whereas the second was markedly delayed, occurring several pore volumes (PV) after the breakthrough. This result is not compatible with the classical picture of multilayer adsorption of HMWSPs but suggests that injectivity is controlled solely by the adsorption of minor polymeric species. This hypothesis was confirmed by reinjecting the collected effluents into fresh cores; no second-step Rm increases were observed. Brine injections in HMWSP-treated cores revealed high residual resistance factors (or irreversible permeability reductions, Rk), which can be attributed to the presence of thick polymer-adsorbed layers on the pore surface. Nevertheless, Rk values strongly decreased when increasing the brine-flow rate. This second significant outcome shows that the adsorbed-layer thickness is shear-controlled. These new results should lead to proposing new adapted filtration and injection procedures for HMWSPs, aimed, in particular, at improving their injectivity.

scholarly journals Ion Mobility Spectrometry-Mass Spectrometry (IMS-MS) for on- and off-line analysis of atmospheric gas and aerosol species

2016 ◽  
Author(s):  
Jordan E. Krechmer ◽  
Michael Groessl ◽  
Xuan Zhang ◽  
Heikki Junninen ◽  
Paola Massoli ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Measurement Techniques ◽  
Molecular Ions ◽  
Molecular Structures ◽  
Water Soluble ◽  
Oxidation Products ◽  
Time Resolved ◽  
Organic Species

Abstract. Measurement techniques that provide molecular-level information are needed to elucidate the multi-phase processes that produce secondary organic aerosol (SOA) species in the atmosphere. Here we demonstrate the application of ion mobility spectrometry-mass spectrometry (IMS-MS) to the simultaneous characterization of the elemental composition and molecular structures of organic species in the gas and particulate phases. Molecular ions of gas-phase organic species are measured online with IMS-MS after ionization with a custom build nitrate chemical ionization (CI) source. This CI-IMS-MS technique is used to obtain time-resolved measurements (5 min) of highly oxidized organic molecules during the 2013 Southern Oxidant and Aerosol Study (SOAS) ambient field campaign in the forested SE US. The ambient IMS-MS signals are consistent with laboratory IMS-MS spectra obtained from single-component carboxylic acids and multicomponent mixtures of isoprene and monoterpene oxidation products. Mass-mobility correlations in the 2-dimensional IMS-MS space provide a means of identifying ions with similar molecular structures within complex mass spectra and are used to separate and identify monoterpene oxidation products in the ambient data that are produced from different chemical pathways. Water-soluble organic carbon (WSOC) constituents of fine aerosol particles that are not resolvable with standard analytical separation methods, such as liquid chromatography (LC), are shown to be separable with IMS-MS coupled to an electrospray ionization (ESI) source. The capability to use ion mobility to differentiate between isomers is demonstrated for organosulfates derived from the reactive uptake of isomers of isoprene epoxydiols (IEPOX) onto wet acidic sulfate aerosol. Controlled fragmentation of precursor ions by collisional dissociation (CID) in the transfer region between the IMS and the MS is used to validate MS peak assignments, elucidate structures of oligomers, and confirm the presence of the organosulfate functional group.

Effect of water-soluble cross-linker on the growth and properties of ethyl acrylate-methacrylic acid emulsion opolymer particles

2000 ◽  
Vol 278 (12) ◽  
pp. 1205-1210
Author(s):  
J. Šňupárek ◽  
L. Mrkvičková ◽  
O. Quadrat ◽  
Z. Walterová ◽  
P. Bradna
Keyword(s):  
Methacrylic Acid ◽  
Ethyl Acrylate ◽  
Water Soluble ◽  
Effect Of Water ◽  
Cross Linker

Water soluble derivatives of platinum carbonyl Chini clusters: synthesis, molecular structures and cytotoxicity of [Pt12(CO)20(PTA)4]2− and [Pt15(CO)25(PTA)5]2−

2018 ◽  
Vol 47 (13) ◽  
pp. 4467-4477 ◽  
Author(s):  
Lucinda K. Batchelor ◽  
Beatrice Berti ◽  
Cristiana Cesari ◽  
Iacopo Ciabatti ◽  
Paul J. Dyson ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Human Cancer ◽  
Molecular Structures ◽  
Water Soluble ◽  
Human Cancer Cells ◽  
Derivatives Of

The cytotoxicity towards human cancer cells of water soluble Chini clusters is reported.

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