Phase Behaviour and FTIR Spectra of Ionic Liquids: The Mixtures of 1-Butyl-1-methylpyrrolidinium Chloride and TaCl5

2008 ◽  
Vol 63 (1-2) ◽  
pp. 66-72 ◽  
Author(s):  
Olga B Babushkina
Keyword(s):  
Thermal Stability ◽  
Ionic Liquids ◽  
Ftir Spectra ◽  
Phase Behaviour ◽  
Molar Ratio ◽  
Ionic Interactions ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
Molar Ratios ◽  
Insight Into

A series of ionic liquids consisting of 1-butyl-1-methylpyrrolidinium chloride (Pyr14Cl) and TaCl5 at molar ratios of Pyr14Cl in the range of 0.85 - 0.20 was synthesized. They exhibit potential application as electrolytes for the electrochemical deposition of tantalum. The thermal behaviour of the Pyr14Cl-TaCl5 mixtures was investigated, using differential scanning calorimetry (DSC) to estimate the range of thermal stability and to determine the optimal compositions for electrochemical trials. The Pyr14Cl-TaCl5 mixtures formed stoichiometric 3 : 2 and 2 : 3 crystalline phases with melting points of 70 °C and 130 °C, respectively, characterized by entropies of fusion of 13.6 JK−1 mol−1 and 10.1 JK−1 mol−1. The mixtures with molar fractions of Pyr14Cl equal to 0.60 and 0.40 were clear and transparent liquids and had the lowest viscosity; they were the most suitable for electrochemical applications. FTIR spectra of the Pyr14Cl-TaCl5 mixtures allowed to get insight into inter-ionic interactions and the nature of formation of these ionic liquids as a function of the molar ratio of the components.

Effect of boric acid on thermal stability of poly (acrylonitrile-methyl acrylate)

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Na Han ◽  
Xingxiang Zhang
Keyword(s):  
Thermal Stability ◽  
Boric Acid ◽  
Methyl Acrylate ◽  
Gel Permeation Chromatography ◽  
Decomposition Temperature ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Molar Ratios ◽  
Thermal Stability Of

AbstractA series of acrylonitrile(AN)-methyl acrylate (MA) copolymers (AN/MA) with molar ratios of 100/0-70/30 were synthesized by water depositing polymerization. One to three percent of boric acid (BA) was adopted as a stabilizer to enhance the thermal stability of AN/MA. The copolymers and the mixtures of copolymers treated with BA were characterized by using Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (1H NMR), Gel Permeation Chromatography (GPC), Differential Scanning Calorimetry (DSC), Thermogravimetry (TG), X-ray diffraction (XRD) and Optic Microscope. The results show that melting point (Tm), glass transition temperature (Tg) and crystallinity of the copolymer decreased while decomposition temperature (Td) increased with the increase of MA content. Tm of AN/MA dropped to 174 °C and Td rose up to 321 °C when 15 mol% MA was incorporated. It was worthy to note that Tm of the copolymers increased conspicuously after being treated with BA. Stability of AN/MA with a molar ratio of 85/15 containing 1 wt% BA improved remarkably. The mixture can be kept stable up to 30 min at 220 °C.

scholarly journals Unexpected Intrinsic Lability of Thiol-Functionalized Carboxylate Imidazolium Ionic Liquids

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3571
Author(s):  
Andrea Mezzetta ◽  
Lorenzo Poderelli ◽  
Felicia D’Andrea ◽  
Christian Silvio Pomelli ◽  
Cinzia Chiappe ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Ionic Liquids ◽  
Side Reaction ◽  
Switching Systems ◽  
Reaction Conditions ◽  
Imidazolium Ionic Liquids ◽  
Methyl Carbonate ◽  
Imidazolium Ring ◽  
Redox Switching ◽  
Insight Into

New thiol-functionalized carboxylate ionic liquids (ILs), varying both for the cation and for the anion structures, have been prepared as new potential redox switching systems by reacting either 3-mercapto propionic acid (3-MPA) or N-acetyl-cysteine (NAC) with commercially available methyl carbonate ILs. Different ratios of thiol/disulfide ILs were obtained depending both on the acid employed in the neutralization reaction and on the reaction conditions used. Surprisingly, the imidazolium ILs displayed limited thermal stability which resulted in the formation of an imidazole 2-thione and a new sulfide ionic liquid. Conversely, the formation of the imidazole 2-thione was not observed when phosphonium disulfide ILs were heated, thus confirming the involvement of the imidazolium ring in an unexpected side reaction. An insight into the mechanism of the decomposition has been provided by means of DFT calculations.

Systematic evaluation of pH and thermoresponsive poly(n-isopropylacrylamide-chitosan-fluorescein) microgel

e-Polymers ◽  
2017 ◽  
Vol 17 (5) ◽  
pp. 399-408 ◽  
Author(s):  
Pedro Hernández ◽  
Armando Lucero-Acuña ◽  
Cindy Alejandra Gutiérrez-Valenzuela ◽  
Ramón Moreno ◽  
Reynaldo Esquivel
Keyword(s):  
Biomedical Application ◽  
Systematic Evaluation ◽  
Molar Ratio ◽  
Solution Temperature ◽  
Stimuli Responsive ◽  
Scanning Calorimetry ◽  
Molar Ratios ◽  
Stimuli Responsive Polymers ◽  
Wide Range ◽  
Low Molecular Weight Chitosan

AbstractThe interesting properties of stimuli-responsive polymers lead to a wide range of possibilities in design and engineering of functional material for the biomedical application. A systematic approach focused on the evaluation of the physical properties of multiresponse (pH and temperature) PNIPAM was reported in this work. The effect of three different molar ratios of poly(n-isopropylacrylamide): chitosan (1:49, 1:99 and 1:198) were evaluated and labeled correspondingly as PC1F, PC2F, and PC3F. An increase in the lower critical solution temperature (LCST) of sample PC1F (34°C) was observed by differential scanning calorimetry (DSC). The presence of low molecular weight chitosan (LMWC) full-interpenetrating polymer (Full-IPN) segments in poly(n-isopropylacrylamide) was confirmed by Fourier-transform infrared spectroscopy (FT-IR). The hydrogel’s water capture was analyzed by two models of swelling, the power law model and a model that considers the relaxation of polymeric chains of the hydrogel, finding good correlations with experimental data in both cases. Sample PC3F resulted with higher swellability, increasing the weight of the hydrogel around seven times. Hydrogel pH-sensibility was confirmed placing the samples at different pH environments, with an apparent increase in swellability for acidic conditions, confirming the highest swellability for sample PC3F, due to hydrogen bonds boosted by chitosan high molar ratio. Based on these results, the hydrogel obtained has potential as a thermo-pH triggered hydrogel in drug delivery applications.

Morphology and Structure of Aluminum Substituted C-S-H Synthesized by Reaction of Alkali Silicate and Calcium Nitrate Aqueous Solution

2011 ◽  
Vol 287-290 ◽  
pp. 1193-1196 ◽  
Author(s):  
Yong Jia He ◽  
Lin Nu Lu ◽  
Jian Ming Zhang ◽  
Shu Guang Hu
Keyword(s):  
Calcium Nitrate ◽  
Nitrogen Adsorption ◽  
Ftir Spectra ◽  
Wave Number ◽  
Molar Ratio ◽  
Aluminum Ion ◽  
Molar Ratios ◽  
Structure And Morphology ◽  
Morphology And Structure ◽  
Scanning Electron

Synthetic C–S–H and C-A-S-H samples with different Ca/Si molar ratios (1.0 and 1.5) were prepared by precipitation from solution. The effects of incorporations of aluminum ion into C-S-H gels on their microstructure were studied by applying Fourier Transform Infrared Spectroscopy (FTIR), BET nitrogen adsorption and scanning electron microscopy (SEM). Results show that in FTIR spectra, peaks nearing 970 cm-1 and 450 cm-1 wave number change obviously with the substitution of Al3+into C/S1.0 C-S-H. In BET diagram, it also can be found that the substitution of Al3+into C/S1.0 C-S-H lower the specific surface area. Furthermore, SEM graphs also show that the morphology change in C/S=1.0 C-S-H after the substitution of aluminum ion. However, little difference can be found in FTIR spectra and BET diagrams after Al3+ doped into C/S1.5 C-S-H. So, it can be concluded that the effects of the substitution of aluminum ion on the structure and morphology of C-S-H are affected by Ca/Si molar ratio

scholarly journals The difluoromethylene (CF2) group in aliphatic chains: Synthesis and conformational preference of palmitic acids and nonadecane containing CF2 groups

2014 ◽  
Vol 10 ◽  
pp. 18-25 ◽  
Author(s):  
Yi Wang ◽  
Ricardo Callejo ◽  
Alexandra M Z Slawin ◽  
David O’Hagan
Keyword(s):  
Palmitic Acid ◽  
Conformational Stability ◽  
Phase Behaviour ◽  
Aliphatic Chain ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
Dipolar Relaxation ◽  
Design Modification ◽  
Palmitic Acids ◽  
Pure Hydrocarbon

The syntheses of palmitic acids and a nonadecane are reported with CF2 groups located 1,3 or 1,4 to each other along the aliphatic chain. Specifically 8,8,10,10- and 8,8,11,11-tetrafluorohexadecanoic acids (6b and 6c) are prepared as well as the singly modified analogue 8,8-difluorohexadecanoic acid (6a). Also 8,8,11,11-tetrafluorononadecane (27) is prepared as a pure hydrocarbon containing a 1,4-di-CF2 motif. The modified palmitic acids are characterized by differential scanning calorimetry (DSC) to determine melting points and phase behaviour relative to palmitic acid (62.5 °C). It emerges that 6c, with the CF2 groups placed 1,4- to each other, has a significantly higher melting point (89.9 °C) when compared to the other analogues and palmitic acid itself. It is a crystalline compound and the structure reveals an extended anti-zig-zag chain. Similarly 8,8,11,11-tetrafluorononadecane (27) adopts an extended anti-zig-zag structure. This is rationalized by dipolar relaxation between the two CF2 groups placed 1,4 to each other in the extended anti-zig-zag chain and suggests a design modification for long chain aliphatics which can introduce conformational stability.

scholarly journals An insight into thermal stability of DNA in hydrated ionic liquids from multi-wavelengths UV Resonance Raman experiments

2021 ◽  
Author(s):  
Barbara Rossi ◽  
Mariagrazia Tortora ◽  
Sara Catalini ◽  
Jacopo Vigna ◽  
Ines Mancini ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Ionic Liquids ◽  
Biomedical Applications ◽  
Resonance Raman ◽  
Native Structure ◽  
Uv Resonance Raman ◽  
Alternative Solvents ◽  
Long Time ◽  
Thermal Stability Of ◽  
Insight Into

The utility of Ionic liquids (ILs) as alternative solvents for stabilizing and preserving for a long time the native structure of DNA may be envisaged for biotechnological and biomedical applications...

Insight into the Interactions That Control the Phase Behaviour of New Aqueous Biphasic Systems Composed of Polyethylene Glycol Polymers and Ionic Liquids

2012 ◽  
Vol 18 (6) ◽  
pp. 1831-1839 ◽  
Author(s):  
Mara G. Freire ◽  
Jorge F. B. Pereira ◽  
María Francisco ◽  
Héctor Rodríguez ◽  
Luís Paulo N. Rebelo ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Polyethylene Glycol ◽  
Phase Behaviour ◽  
Aqueous Biphasic Systems ◽  
Aqueous Biphasic ◽  
Biphasic Systems ◽  
Insight Into

Ionic Liquids Based on Imidazolium and Pyrrolidinium Salts of the Tricyanomethanide Anion

2004 ◽  
Vol 57 (2) ◽  
pp. 121 ◽  
Author(s):  
Stewart A. Forsyth ◽  
Stuart R. Batten ◽  
Qing Dai ◽  
Douglas R. MacFarlane
Keyword(s):  
Thermal Stability ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Thermal Analyses ◽  
Melting Points ◽  
Ambient Temperatures ◽  
Electrochemical Window ◽  
Potential Use

A novel series of tricyanomethanide ionic liquids have been prepared and characterized for potential use as ionic liquid solvents. Full thermal analyses of all salts at ambient and sub-ambient temperatures are reported (melting points –17° to 160°C). The thermal stability and decomposition temperatures are also presented (Tdecomp ≈ 300°C). An electrochemical window of ~3 V has been established and the conductivity measured over a range of temperatures (20 mS cm–1 at 25°C).

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