Mixtures Of N-methylpyrrolidone Research Articles

Toward Thin Dielectric Films of Polyetherimide Electrodeposited from Aqueous Emulsions of the Polymer

Miniaturized, high power electronic devices are needed for a variety of applications. Although, the miniaturization of these devices is challenging. For instance, high power capacitors need to sustain high electric fields, with typically several hundred volts across micrometric dielectric layers. Among the most promising materials for this application, polyetherimide (PEI) has a number of desired characteristics such as adequate electrical properties, good chemical and mechanical resistance with thermal stability up to 170°C.Spin-coating is the conventional technique used in the microelectronics industry for polymer thin film deposition. However, this technique is not appropriate to form conformal deposits on 3D-structured substrates. To overcome this limitation, we investigate an electrochemical deposition process of PEI in which the electrolyte is an aqueous emulsion formed from organic droplets containing the polymer [1]. In this work, a pulsed voltage below 2 V/ECS, was applied for the deposition of PEI on Cu metal surfaces. The influence of deposition conditions on the thickness and surface smoothness of the deposit was thoroughly investigated, identifying the processing window.PEI aqueous emulsions were synthesized as follows, after the raw material dissolved in a mixture of N-methylpyrrolidone and acetophenone, N-methylpiperazine was added to be grafted on the imide groups of the polymeric chains. The PEI emulsions were subsequently produced by ultrasonic mixing [2] of the reaction crude with an aqueous solution of lactic acid. During mixing, nanoscale droplets were formed and electrostatically charged by protonation of ternary amine groups of N-methylpiperazine.Critical for the application are the droplet size and stability of the emulsion. These properties were modulated upon stoichiometry of both N-methylpiperazine for the degree of modified imide cycles and lactic acid for the degree of protonation of the amine [1,2]. FTIR and NMR were used to screen the quantity of modified imide groups, displaying that the PEI imide function attack by N-methylpiperazine is quantitative. The protonation was indirectly characterized by measuring the zeta potential of the emulsion [3]. As a result, in an optimized sequence, droplets with hydrodynamic diameters below 200 nm were repeatedly formed with zeta potentials greater than 50 mV. For emulsions containing 3.5 wt% PEI with 64 % modified imide groups and 50 % quaternisation, representing 32 % of the imide cycle initial population. The emulsions were stable for at least twenty-one days at 4°C. This is a significant improvement as compared to the stability reported in the literature [1].Deposition tests were conducted in a 3-electrode electrochemical cell, using a 10-time diluted emulsion, at relatively low voltage, below 2 V/ECS with pulsed DC waveform under mild conditions (room temperature, pH between 3 and 5). The pulses allowed the movement of droplets in the emulsion towards the cathode while minimizing H2 evolution. Under these conditions, a PEI coating was obtained with a thickness of a few micrometers within 600 s. The impact of deposition parameters on coverage and uniformity was also studied in detail.The last process step by removing the N-methylpiperazine and the residual solvents consists in recovering the initial unmodified structure of PEI grafted on the substrate. Curing conditions were chosen according to the previous literature [1] under vacuum. The FTIR spectra of the coated substrate were recorded after curing. From the FTIR spectra, the disappearance of the amide (I and II) peaks after curing and a good peak-for-peak correspondence between the spectrum of the cured polymer and the pristine polymer are observed.This work demonstrates that polymer films can be deposited by an electrochemical process under mild conditions, assuming that a stable emulsion of charged polymer droplets can be formed. The process is well suited to coat 3D structured substrates, in contrast with more conventional techniques for polymer deposition. This original electrodeposition process should allow the realization of integrated capacitors on silicon wafers for the next generation of power electronics devices.

ЭКСТРАКЦИОННАЯ ОЧИСТКА ЛЕГКОГО ГАЗОЙЛЯ КАТАЛИТИЧЕСКОГО КРЕКИНГА ОТ ГЕТЕРОАТОМНЫХ КОМПОНЕНТОВ И ПОЛИАРОМАТИЧЕСКИХ УГЛЕВОДОРОДОВ СМЕСЯМИ N-МЕТИЛПИРРОЛИДОН – ЭТИЛЕНГЛИКОЛЬ

The results of single-stage, as well as two- and three-stage cross-current extraction of sulfurous and nitrogenous components, aromatic and unsaturated hydrocarbons from light catalytic cracking gas oil with mixtures of N-methylpyrrolidone with ethylene glycol composition 80/20, 70/30 and 60/40 wt. % are presented with a mass ratio of extragent : raw materials 1 : 1 and a temperature of 40 оC. The degree of extraction of sulfur compounds at the ethylene glycol content in the extractant is 30 wt. % as a result of single-stage extraction is 70 %, and with three-stage purification - about 90 %, the cetane index of raffinate increases by more than 13 and 19 points, respectively

Study dearomatization of diesel fuel under the infulence of magnetic field by IR spectroscopy

The purification process of polycyclic aromatic hydrocarbons was carried out by extraction of diesel fraction from the primary oil refining using the effect of magnetic field. A mixture of N-methylpyrrolidone with sulfuric acid was used as an extractant. The content of aromatic hydrocarbons in the diesel fraction decreased by 39.8% under normal conditions and by 50.8% under the influence of magnetic field after extraction. The samples were investigated by infrared (IR) spectroscopy method before and after extraction. Vibartional modes corresponding to different atomic bonds have been observed. Deodorization of diesel was determined by interpreting obtained modes.

Removal of Carcinogenic Polycyclic Arenes from Aromatic Softener Oils by Extraction with Dimethyl Sulfoxide and N-Pyrrolidone–Ethylene Glycol Mixed Extractant

Comparative experimental data on the four-step countercurrent extraction treatment of a mixture of naphthene vacuum gas oil and residual extract with dimethyl sulfoxide and with a 90 : 10 (wt %) mixture of N-methylpyrrolidone with ethylene glycol are presented. The mixed extractant based on N-methylpyrrolidone, compared to dimethyl sulfoxide, ensures more exhaustive removal of eight carcinogenic polycyclic arenes, including benzo[a]pyrene, from aromatic softener oil at a lower extractant to feed ratio.

Synthesis of Poly-p-phenylene Terephthalamide (PPTA) in Ionic Liquids

Several ionic liquids (ILs) were tested for their suitability to synthesize the aramid polymer poly-p-phenylene terephthalamide (PPTA) in an attempt to diminish the dependence on the toxic N-methylpyrrolidone (NMP) that is currently used in industry. The room-temperature IL 3-methyl-1-octylimidazolium chloride ([C8MIM][Cl]) showed the highest promise as, with this medium, the polycondensation reaction proceeds with a mechanism similar to how it occurs in the solvent mixture of NMP with CaCl2. With this IL, PPTA polymer with an inherent viscosity of 1.95 dL/g was obtained in a low-temperature polycondensation reaction. This is the highest reported molecular mass of PPTA to date that was obtained by polymerization in an ionic liquid. An extended X-ray absorption fine structure (EXAFS) and solid-state NMR spectroscopic study showed that [C8MIM][Cl] and the current industrial solvent of NMP and CaCl2 show similar characteristics when it comes to the synthesis of PPTA.

The Relationship between Solubility and Transdermal Absorption of Tadalafil.

The aim of this study was to find a relationship between drug solubility and its transdermal permeation and find the best vehicle composition to improve transdermal permeation of Tadalafil. Pure or binary mixtures of commonly used solvents in pharmaceutical sciences including ethanol, glycerin, N-methyl pyrrolidone (NMP), polyethylene glycol (PEG) 400 and propylene glycol (PG) were evaluated for drug solubility and transdermal delivery through the exercised rat skin employing Franz diffusion cells. Tadalafil showed higher solubility in NMP compared to the other solvents. The amount of Tadalafil permeation from the pure vehicles was ranked as follow: Ethanol >glycerin >NMP>PEG 400 >PG. Furthermore, the solubility and transdermal delivery from binary mixtures of NMP and PG were higher than that obtained from pure PG, and accordingly, both increased with increasing NMP concentration in the binary solvent mixtures. The Flux values were determined as following order for Ethanol>NMP>glycerin>PG>PEG 400. Generally, increase in Tadalafil solubility resulted in a decrease in its skin penetration rate and amount. However, NMP exhibited substantial drug skin penetration rate and amount accompanying with appropriate drug solvency. In conclusion, the results of this study introduced NMP as a solvent suitable for application in the formulation of topically applied drug delivery systems.

Effect of solvents on the morphology of NiCo2O4/graphene nanostructures for electrochemical pseudocapacitor application

The large internal surface areas and outstanding electrical and mechanical properties of graphene have prompted to blend graphene with NiCo2O4 to fabricate nanostructured NiCo2O4/graphene composites for supercapacitor applications. The use of graphene as blending with NiCo2O4 enhances the specific capacitance and rate capability and improves the cyclic performance when compared to the pristine NiCo2O4 material. Here, we synthesized two different nanostructured morphologies of NiCo2O4 on graphene sheets by solvothermal method. It has been suggested that the morphologies of oxides are greatly influenced by dielectric constant, thermal conductivity, and viscosity of solvents employed during the synthesis. In order to test this concept, we have synthesized nanostructured NiCo2O4 on graphene sheets by facile solvothermal method using N-methyl pyrrolidone and N,N-dimethylformamide solvents with water. We find that mixture of N-methyl pyrrolidone and water solvent favored the formation of nanonet-like NiCo2O4/graphene (NiCoO-net) whereas mixture of N,N-dimethylformamide and water solvent produced microsphere-like NiCo2O4/graphene (NiCoO-sphere). Electrochemical pseudocapacitance behavior of the two NiCo2O4/graphene electrode materials was studied by cyclic voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy techniques. The supercapacitance measurements on NiCoO-net and NiCoO-sphere electrodes showed specific capacitance values of 1060 and 855 F g−1, respectively, at the current density of 1.5 A g−1. The capacitance retention of NiCoO-net electrode is 93 % while that of NiCoO-sphere electrode is 77 % after long-term 5000 charge-discharge cycles at high current density of 10 A g−1.

Production of automobile gasolines from Astrakhan gas condensate residual fuel oil

The possibility of use of Astrakhan gas condensate residue above 350°C as feedstock for catalytic cracking has been explored. The feedstock was submitted to extraction cleaning with a mixture of N-methylpyrrolidone and heptane to improve the ecological properties of the cracking products.

Evaluation of Some Organic Solvents for Refining Diesel Fuel Fraction

Using solvent extraction, we studied the oil refining process of diesel fuel fraction (boiling range 212°C to 343°C) crude oil from the Suez oil petroleum company (Cairo, Egypt). We used organic solvents such as dimethylsulfoxide (DMSO), furfural, mixtures of N-methylpyrrolidone (NMP) + ethylene glycol (EG) as an antisolvent as well as dimethylformamide (DMF) + (EG). In addition, we determined the critical solution temperature (CST) of the examined solvents with the feedstock. The efficiency of pure and mixed solvents has been evaluated in terms of yield and characteristics of the raffinates obtained. We evaluated the selectivity (β) as well as the solvent power (K) of the examined solvents. The ternary miscibility diagrams of the systems' diesel fuel fraction (pure and mixed solvents) have also been determined.

Extraction treatment of catalytic cracking feedstock

In extraction treatment of the 470°C-EP cut of heavy vacuum gasoil with a mixture of N-methylpyrrolidone and octane, the carbon residue of the gasoil decreases from 4 to 1.75 wt. %. In catalytic cracking of such treated feedstock, the relative yield of naphtha and diesel cuts increases by 10 and 37% and coking decreases by 30%.

Characterization of oil shales by extraction with N-methylpyrrolidone

Two Turkish oil shales were extracted at room temperature with N-methylpyrrolidone and with a mixture of N-methylpyrrolidone and carbon disulfide. The extracts were analysed by chromatography and spectroscopy. The aromatic compounds contained small clusters of aromatic rings highly substituted with branched alkyl groups. The alkane geomarkers are consistent with immature sediments derived from terrestrial higher plants and aquatic material deposited under saline conditions.

Drying of Dielectric Resin Coatings in the Presence of Polycondensation

ABSTRACT Drying of dielectric resin coatings is accompanied simultaneously by evaporation of multicomponent solvents and polycondensation from monomers. The characteristic of the drying is studied experimentally. As a test sample, a vanish consisting of trimellitic acid anhydride and 4.41-diphenylmethane diisocyanate dissolved in the mixture of N-methylpyrrolidone and xylene is coated on an aluminum pan. The sample is subjected in drying in two types of dryers: hot air heating and radiation heating. The constant drying rate period is not observed in any run. The maximum drying rate of the sample is lower than the evaporation rate from the solvent layer with no resin. There are remarkable fluctuations in the drying rate in the decreasing drying rate period. The fluctuations are caused by bubble formation. The progress of the reaction can be followed by IR spectroscopic analysis. From these results it is suggested that removal of the solvent and the product is inhibited by the formation of a polymer skin on the surface and it makes control of drying difficult.

Physical Gelation of Amorphous Polymers in a Mixture of Solvent and Nonsolvent

The formation of phase inversion membranes made by immersion precipitation from a ternary system consisting of an amorphous polymer, a solvent, and a nonsolvent has been rationalized by assuming a gelation process. The treatise is based on a hypothesis developed by Berghmans for a binary system consisting of a polymer and a solvent. The ternary phase diagram for the mixture of H2O−NMP (N-methylpyrrolidone)−PES (poly(ether sulfone)) was determined at 25 °C. In this system three boundaries could be identified, i.e., a vitrification, a gelation, and a binodal boundary. It was found that for this system and a system composed of H2O−DMAC (N,N-dimethylacetamide)−PSF (polysulfone), vitrification is the only mechanism responsible for the structure fixation of membranes prepared by liquid−liquid demixing due to immersion precipitation. For the system of MPD (2-methyl-2,4-pentanediol)−NMP−PES, it was found that a membrane can be formed by vitrification as a result of immersion precipitation prior to liquid−liquid demixing. The depressions of the glass transition temperature of PES by the addition of FP (N-formylpiperidine), DMSO (dimethyl sulfoxide), DMAC, or NMP as well as by a mixture of NMP and water are determined.

Solubility of hydrogen sulfide in mixtures of N-methylpyrrolidone with alkanolamines

Murrieta-Guevara F., Rebolledo-Libreros E. and Trejo A., 1992. Solubility of hydrogen sulfide in mixtures of N-methylpyrrolidone with alkanolamines. Fluid Phase Equilibria, 73: 167-174. The solubility of hydrogen sulfide in binary mixtures of N-methylpyrrolidone with monoethanolamine and diethanolamine was determined at temperatures between 298.15 and 373.15 K in the pressure range 20–1300 kPa. The mixtures studied were 15 wt.% with monoethanolamine and 30 wt.% with diethanolamine. The experimental results are reported as the partial pressure of hydrogen sulfide against its mole fraction in the liquid phase. Values of the enthalpy of solution were derived from the solubility data.

Synthesis and Properties of Polyamides of 2,2′-[Isopropylidenebis-(p-phenyleneoxy)] diacetic Acid

Abstract A group of six semiaromatic polyamides of 2,2′-[isopropylidenebis-(p-phenyleneoxy)]diacetic acid (Bisacid A2) were synthesized by low-temperature solution polycondensation techniques. Six different diamines were condensed independently with Bisacid A2 chloride in a mixture of N-methylpyrrolidone (NMP and hexamethylhosphoramide (HMPA). The polymers were obtained in 82–95% yield and possessed inherent viscosities in the range from 0.32 to 0.63 dL/g. The polyamides were characterized by IR and 'H-NMR spectra. The molecular weight and molecular weight distribution of the polyamides were determined by gel-permeation chromatography. The thermal stability, thermal degradation kinetics, crystallinity, density, and solubility were also determined. A model diamide (MDA) was synthesized from aniline and Bisacid A2 chloride to confirm the formation of polyamides from diamines.

Polymer solutions from latexes

AbstractIn order to characterize a polymer by its reduced viscosity, it is necessary to put it into solution. For polymer made by emulsion polymerization, this usually involves coagulating the latex, washing and drying the coagulum, and then dissolving the residue in an organic solvent. The method fails when the polymer crosslinks on drying, as is the case with some adhesive resins. The method proposed here uses mixtures of N‐methylpyrrolidone (NMP) and tetrahydrofuran (THF) to put the polymer directly into solution without removing the water. The technique is applicable to many polymers and copolymers of ethyl acrylate and vinyl acetate.