DMF), N,N-dimethylacetamide Research Articles

Cosolvent-assisted construction of high-performance reverse osmosis membranes with multilayer nanovoid structures: Effect of amides in aqueous phase

The cosolvent-assisted interfacial polymerization (CAIP) has garnered significant attention due to its capacity to easily and effectively modify the performance of polyamide (PA) reverse osmosis (RO) membranes. To gain deeper understanding of the mechanism of a specific type of cosolvents on the IP reaction, namely N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N,N-dimethylpropionamide (DMPr) were used as aqueous-phase cosolvents to systematically investigate their effects on the membrane structures and properties under different conditions. Amide cosolvents in the aqueous phase facilitated the diffusion of the amine monomer and the formation of nanovoids within the PA layer as the C-chain length of amides increased. When 1,2-dichloroethane was also included in the organic phase, the extent of the two-phase miscible zone was further increased with its assistance, which contributed to generating the larger nanovoids within the layer, thicker PA layer and extensive exterior PA layers, as well as significantly enhancing the water permeability and selectivity of membranes. Importantly, this study successfully prepared high-performance RO membranes with multilayer nanovoid structures in situ by introducing cosolvents in the IP reaction with permeability up to 2.26 L·m−2·h−1·bar−1, providing theoretical and experimental bases for further enrichment of CAIP.

CuS modified PEDOT:PSS grafted paper-based electrochemical immunosensor for EpCAM biomarker detection

A novel CuS grafted PEDOT:PSS conducting paper-based electrochemical immunosensor has been successfully fabricated for the detection of EpCAM antigen. Electrical conductivity is further improved by doping the CuS@PEDOT:PSS/WP electrode with different organic solvents such as N,N-dimethyl formamide (DMF), N,N-dimethyl acetamide (DMA), ethylene glycol (EG) and dimetyl sulfoxide (DMSO). It is observed that DMSO doped conducting paper shows the highest conductivity (6.1 × 10−2 S/cm) among all these solvents. This low cost, biodegradable electrochemical paper-based immunosensor (BSA/anti-EpCAM/EP) possesses a broad linear range from 0.01 pg/mL to 1000 ng/mL for EpCAM antigen detection. The immunosensor is found to have high sensitivity of 104.31 μA pg−1 mL. This conducting paper based immunosensor is further used to detect EpCAM antigen in human serum samples, thereby confirming a cost effective clinical tool over other costly conventional techniques.

Revisiting Amides as Cosolvents for Flame Resistant Sodium Bis(oxalato)borate in Triethyl Phosphate Electrolyte

AbstractIn selecting electrolytes for Na‐ion batteries, simply importing the analogue of common lithium‐ion battery electrolytes to sodium‐ion batteries does not address safety concerns like toxicity and flammability. Electrolytes based on sodium bis(oxalato)borate (NaBOB) in organophosphates like triethyl phosphate (TEP) largely alleviate these specific safety concerns. However, it may be beneficial to obtain solutions with higher ionic conductivities than NaBOB in TEP, and compare the performance in Na‐ion batteries with high mass loading electrodes. Here, we have shown that N,N‐dimethyl formamide (DMF), N,N‐dimethyl acetamide (DMAc), and N‐methyl pyrrolidone (NMP) cosolvents almost double the ionic conductivity (from ~3.5 mS/cm to ~7 mS/cm) without sacrificing the flame‐retarding properties of the base NaBOB in TEP electrolyte. The physical properties of these cosolvent electrolyte mixtures are investigated, along with the electrochemical performance of these electrolytes full‐cells based on hard carbon anodes and Prussian white cathodes with near‐commercial areal capacity (~2 mAh/cm2).

Human biomonitoring guidance values (HBM-GVs) for priority substances under the HBM4EU initiative - New values derivation for deltamethrin and cyfluthrin and overall results.

The European Initiative HBM4EU aimed to further establish human biomonitoring across Europe as an important tool for determining population exposure to chemicals and as part of health-related risk assessments, thus making it applicable for policy advice. Not only should analytical methods and survey design be harmonized and quality assured, but also the evaluation of human biomonitoring data. For the health-related interpretation of the data within HBM4EU, a strategy for deriving health-based human biomonitoring guidance values (HBM-GVs) for both the general population and workers was agreed on. On this basis, HBM-GVs for exposure biomarkers of 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH), phthalates (diethyl hexyl phthalate (DEHP), di-n-butyl phthalate (DnBP), diisobutyl phthalate (DiBP), butyl benzyl phthalate (BBzP), and bis-(2-propylheptyl) phthalate (DPHP)), bisphenols A and S, pyrethroids (deltamethrin and cyfluthrin), solvents (1-methyl-2-pyrrolidone (NMP), 1-ethylpyrrolidin-2-one (NEP), N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC)), the heavy metal cadmium and the mycotoxin deoxynivalenol (DON) were developed and assigned a level of confidence. The approach to HBM-GV derivations, results, and limitations in data interpretation with special focus on the pyrethroids are presented in this paper.

Dihydrolevoglucosenone (Cyrene™), a new possibility of an environmentally compatible solvent in synthetic organic electrochemistry.

Dihydrolevoglucosenone (DLG or Cyrene™) solvent is a green dipolar solvent produced from cellulose waste. Different studies have demonstrated that it can successfully replace dipolar solvents, such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA) and N-methylpyrrolidinone (NMP), in a variety of chemical reactions. In this paper, the first application of DLG in organic electrosynthesis is described, with results of its use in the electrochemical reduction of benzophenone derivatives (ca. E = -1.75 V vs. Ag/AgCl), as a greener alternative to other dipolar solvents with environmental concerns. Conductivity measurements show that the solvent presents conductivity and viscosity limitations that can be overcome by using EtOH as a cosolvent. The DLG/EtOH mixture resulted in a convenient solvent to carry out galvanostatic electroreductions of starting materials that exhibit high potential value. Furthermore, the reaction pathway (1e- or 2e-) was found to be dependent on the supporting electrolyte used; TBABF4 favored 2e- reduction to the corresponding alcohol (52-85%), whereas LiClO4 promoted C-C pinacolic coupling (47-70%).

Thermodynamic analysis of hydrogen-bonded polymer complexation with isothermal titration calorimetry

Rigorous thermodynamic analysis of polymer complexation is challenging due to the possible kinetically frozen state, complicated chain conformation, and slow chain relaxation. In this work, we study the complexation of poly(acrylic acid) (PAA) with poly(vinylpyrrolidone) (PVPON), poly(2-ethyl-2-oxazoline) (PEOX) and poly(ethylene oxide) (PEO) in acidic water and in organic solvents, including protic solvents (methanol (MeOH), ethanol (EtOH)), and aprotic solvents (N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAC), 1-methyl-2-pyrrolidone (NMP), and dimethyl sulfoxide (DMSO)) with isothermal titration calorimetry (ITC). In DMF, complexation of PAA and PVPON has moderate heat releasing and the effect of kinetically frozen structure is negligible, and the ITC data meet the basic standard to be used for analyzing and estimating thermodynamic parameters, and enthalpy, entropy and Gibbs free energy are calculated to be −1.5 kJ/mol, 45 J/(mol⋅K), and −15 kJ/mol respectively. Furthermore, the effects of temperature, chain length contrast, and concentration on the complexation of PAA with PVPON in DMF are studied. The work provides a theoretical method how to evaluate the ITC dada of hydrogen-bonding polymer complexation for thermodynamic analysis and strengthens the understanding of polymer complex.

Microstructures and properties of PVDF membranes: effect of the solvent

The polyvinylidene fluoride (PVDF) membranes were synthesized using immersion precipitation technique. The effect of four solvents, N, N-dimethyl formamide (DMF), N, N-dimethylacetamide (DMAC), N-methyl-2-pyrrolidone (NMP), and dimethyl sulfoxide (DMSO) on the water flux and beef serum albumin (BSA) rejection efficiency was reported. The structure and morphology of PVDF membranes were studied using Scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and water contact angle measurements. The cross-section of a membrane formed in a DMF as a solvent exhibit a spongy/fingerlike hybrid structure, while DMSO favors the formation of more porous structure. The increase in the solvent mass fraction facilitates liquid phase separation and solution casting, and changes the structure of PVDF membrane from denser, bicontinuous structure to a looser, stacked structure. Moreover, the results revealed that the properties of PVDF membranes sub-layer are controlled by the diffusion rate of the nonsolvent. The membrane with the best performance was prepared using 80% DMF (mass fraction) as a solvent, and it reached water flux of 66 L·m−2·h−1, and 91.53% BSA rejection efficiency.

Residual solvent induced physical morphology and gas permeation in polyamide-imide membrane: Experimental investigation and molecular simulations

The present study focuses on understanding various residual solvent effects on the physical morphology and separation characteristics of polyamide-imide (Torlon) membranes. The dense membranes were indigenously synthesized by phase inversion technique using various solvents including, N,N-dimethyl formamide (DMF), N,N-dimethyl acetamide (DMAc) and N-methyl pyrrolidone (NMP) respectively. The effect of various solvents on the physical morphology and separation characteristics were studied using a combination of both experimental techniques and atomistic simulations. The Hansen solubility and Floury-Huggins parameters were used to understand the polymer–solvent interactions and further extended to correlated to separation characteristics. Scanning electron microscope (SEM) and atomic force microscopy (AFM) methods were used to investigate the resulted physical morphology of the membranes. Thermogravimetric analysis (TGA) and 1H NMR spectra revealed residual solvent, hydrogen-bonding interactions with the Torlon polymer membrane. The experimental gas permeation studies demonstrated that the CO2 permeability in Torlon membranes follows the order T-NMP > T-DMAc > T-DMF. However, the membrane with the T-DMAc solvent exhibited higher ideal selectivity of 34.65 at 12.5 bar for CO2/CH4 separation due to the lower diffusion coefficient of CH4 in the presence of residual DMAc. The predicted solubility and diffusion coefficients of CO2 and CH4 were shown to be in good agreement with the experimental results. Additionally, structural analysis of simulated models provided further insights into residual solvent effects on the microscopic properties and gas permeation. Overall, the Torlon membrane with the residual DMAc solvent showed positive effects on the transport properties and in turn enhance the diffusive selectivity.

Solubility, MD simulation, thermodynamic properties and solvent effect of perphenazine (Form I) in eleven neat organic solvents ranged from 278.15 K to 318.15 K

Perphenazine has rather effective in the treatment of mental illness. In this work, the solid-liquid equilibrium data of perphenazine in eleven organic neat solvents were determined by laser dynamic method under the atmospheric pressure and temperature range of 278.15 K ∼ 318.15 K. The selected solvents were n-propanol, n-butyl alcohol, methyl acetate, ethyl acetate, n-propyl acetate, n-amyl acetate, N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAC), acetone, 2-methoxyethanol, glycol ether, respectively. From the results, the solubility of perphenazine is all positively correlated with temperature. Separately, we have adopted the KAT-LSER model and molecular dynamics simulation to investigate the influence of solvent effects and solute-solvent interaction on solute solubility. Meanwhile, there were four activity coefficient models being used to correlate the solubility data and Average relative deviation of models are 4.13% (Margules model), 3.94% (NRTL model), 4.49% (NRTL-SAC model) and 3.06% (UNIQUAC model), respectively, all of which do not exceed 5%. It manifests that the four activity coefficient models can fit the experimental values well, in which the UNIQUAC model gives the best regression effect. Moreover, the apparent thermodynamic properties(△solG°, △solH° and △solS°) of perphenazine in various solvents were calculated by Van’t Hoff equation. In accordance with the analysis and calculation of dissolution, the dissolution process is an endothermic entropy-driven process. This research can provide basic data for the crystallization process of perphenazine.

Facile biodegradation of N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone by source-derived Bacillus strain APS1 for water reclamation and reuse

Large volume of hazardous aprotic polar solvents such as N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) are released to the environment through wastewater stream, generated from industries which include polymer membrane industries. Biodegradation of these solvents by bacterial strains is a convenient process but inherent toxicity of these solvents at high concentrations often limits the efficiency of the process. Current work reports a facile biodegradation of DMF, DMAc and NMP at high concentrations employing free cells of Bacillus cereus APS1 strain, isolated from DMF rich wastewater. The newly isolated strain is capable of degrading these solvents utilizing them as sole carbon and nitrogen source. The free cells of APS1 are highly tolerant to DMF concentration as high as 35000 mg/L. Biodegradation of solvents is monitored by refractive index, HPLC and 1H NMR spectroscopy. Effect of pH of the wastewater, cell growth and concentration of the solvents is evaluated. Almost complete biodegradation of DMF(30000 mg/L) present in wastewater occurs within 48 h, while 192 h is required at DMF concentration of 35000 mg/L. Time required for complete biodegradation of DMAc and NMP at concentration of 10000 mg/L is 72 h and 96 h respectively. In batch mode, the biodegradation efficacy of APS1 remains steady for multiple cycles. Ultrafiltration membranes prepared using reclaimed water and fresh water as nonsolvents show similar morphology and performance. This work shows that a strain isolated from DMF wastewater is advantageous for the biodegradation of DMF or similar kind of amide containing solvents.

Fluorescence probe with AIE properties for ratiometric/turn off detecting of water in organic solvents and solid state

ABSTRACT Efficient detection of trace water was important before use in water-sensitive reactions. Herein, a fluorescence sensor 1,4-bis((E)-(2-(benzo[d]thiazol-2-yl)hydrazineylidene)methyl)benzene (DHB) was designed and synthesised by a simple one-step reaction using 2-hydrazinobenzothiazole and terephthalaldehyde as raw materials. DHB showed aggregation-induced emission characteristics in solid state and 1,4-dioxane/H2O mixture. In addition, the fluorescent colour changes in IPA and fluorescence quenching in N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), dimethyl sulphoxide (DMSO), glycerine (GI), and 1,3-propanediol (1,3-PDO) were obviously observed with increasing water content, making DHB a highly sensitive fluorescent sensor for water detection with a detection limit of 0.174% for IPA, 0.040% for DMSO, 0.067% for DMF, 0.039% for DMA, 0.069% for 1,3-PDO, and 0.013% for GI, respectively. Further, DHB displayed fluorescence colorimetric response to water in solid state. 1H NMR titration indicated that the sensing mechanism for the detection of trace water was form hydrogen bonds between H2O molecule and amino group of DHB.

A new two-dimensional homochiral cadmium(II) coordination polymer: synthesis, structure determination, optical properties, and fluorescent sensing

A new two-dimensional (2D) homochiral cadmium(II) coordination polymer, {[Cd4(OH)2(L)2(pea)4]·CH3OH} n (1) (pea = (S)-1-phenylethanamine), was solvothermally synthesized based on an enantiomerically pure chiral ligand (S)-5-(((1-carboxy-2-phenylethyl)amino) methyl)isophthalic acid (H3L). Crystal structure analysis shows that 1 is a 2D homochiral framework consisting of coaxial double-helical chains where a pair of left- and right-handed 21 helixes shares tetranuclear Cd cluster subunits [Cd4(μ 3-OH)2]. Topologically, 1 is an interesting 3,6-connected network with the point symbol of (43)2(46·66·83). The thermal stability and solid-state optical properties, including circular dichroism, and nonlinear optical and luminescent properties of 1 were systematically investigated. Furthermore, the fluorescence response of 1 to various common solvents and metal ions was preliminarily studied. Interesting enough, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), acetone and Fe3+ ion have strong quenching effect on the fluorescence of 1, indicating that 1 has certain potential application in the visual detection of these species.

Solubility of Phthalic Acid and o-Toluic Acid in Seven Organic Solvents: Experimental Measurement and Thermodynamic Modeling

In this study, the solubility of phthalic acid and o-toluic acid in propionic acid, N-methylformamide, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), and acetonitrile are measured under atmospheric pressure (101.3 kPa) by the method of laser dynamics. The experimental temperature range is 286.35 to 338.75 K. The measured data shows that the solubility of phthalic acid and o-toluic acid increases with increasing temperature in the temperature range studied. The experimental data are correlated by the Apelblat model, the λh model, and the modified nonrandom two liquid activity coefficient model, and the calculated solubility is in agreement satisfactorily with the measured results. Akaike information criterion analysis results show that the Apelblat model was the most suitable model to correlate the solubility of phthalic acid in propionic acid, N-methylformamide, and DMSO and the solubility of o-toluic acid in propionic acid, DMSO, and NMP; the λh model was the most suitable model to correlate the solubility of phthalic acid in DMF and DMAC and the solubility of o-toluic acid in N-methylformamide and DMF; and the modified NRTL model was the most suitable model to correlate the solubility of phthalic acid in NMP and acetonitrile and the solubility of o-toluic acid in DMAC and acetonitrile.

Thermodynamic analysis and molecular simulation of solid–liquid phase equilibrium of isoprenaline hydrochloride in eleven pure solvents at saturation

In this research, the solubility of isoprenaline hydrochloride (IPN) in eleven neat solvents was investigated by using experimental and molecular dynamic (MD) simulation analysis approaches. The experimental solubility data of IPN in eleven neat solvents of methanol, 2-methoxyethanol, ethanol, 2-ethoxyethanol, n-propanol, 2-propoxyethanol, n-butanol, 2-butoxyethanol, N, N-dimethylformamide (DMF), N-N-Dimethylacetamide (DMAC) and 1-Methyl-2-pyrrolidinone (NMP) were determined by laser monitoring method at temperature range of (278.15 K–323.15 K) under atmospheric pressure. The solubility values were sensitive to temperature, namely, increased monotonously with increasing temperature. The order of IPN solubility at each temperature point in selected solvents is: DMAC > DMF > NMP > methanol > 2-methoxyethanol > ethanol > 2-ethoxyethanol > 2-propoxyethanol > n-propanol > 2-butoxyethanol > n-butanol. Then, the measurement solubility data was correlated by Two-Suffix Margules model, NRTL-SAC model, Yaws model, λh equation and Apelblat equation, respectively. The derived apparent thermodynamic parameters (ΔdisGo, ΔdisHo, ΔdisSo, ζH, ζTS) shown an entropy-driven, endothermic and spontaneous process of dissolution of IPN in all chosen solvents. And the main contribution of ΔdisGo comes from the positive enthalpy according the larger ζH than ζTS. Furthermore, the results of molecular dynamic simulation revealed using radial distribution function (RDF) analysis, which indicated that interactions of solvent–solute have well fitted with solubility order of IPN in selected solvents.

Pretreatment of pussy willow and Korean pine using various ionic liquids and their mixtures with organic solvents for enzymatic saccharification

Different ionic liquids (ILs) and their mixtures with organic solvents (OSs) were investigated to determine their effects on pretreatment for enzymatic saccharification of pussy willow and Korean pine. Combinations of three ILs, namely (1-ethyl-3-methylimidazolium acetate ([EMIM]Ac), 1-butyl-3-methylimidazolium bromide ([BMIM]Br), and 1,3-dimethylimidazolium methyl sulfate ([MMIM]MeSO4)) and three OSs (N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO)) were used. Acremonium cellulase and Optimash BG were used for enzymatic saccharification. The viscosity of ILs and their mixtures with OSs was reduced by adding and increasing the OS amount in mixtures. The viscosity of [BMIM]Br was considerably decreased by the addition of OSs. For both species, the water-soluble fractions (WSFs) obtained using pure ILs decreased with increasing OS content in mixtures. For all co-solvent systems, the WSFs for pussy willow were twice as large as those for Korean pine. For both species, the yields of glucose and xylose were higher for [EMIM]Ac and its mixtures with OSs than for [BMIM]Br, [MMIM]MeSO4, and their mixtures. However, only small differences between glycan and xylose yields among the products pretreated by [BMIM]Br, [MMIM]MeSO4, and their mixtures were observed. The overall xylose yields for pussy willow were higher than those for Korean pine for all pretreatments because xylan is the main hemicellulose component of hardwood.

Measurement and correlation for solubilities of succinic acid, glutaric acid and adipic acid in five organic solvents

In this study, the solid-liquid equilibrium (SLE) data of succinic acid (SA) and glutaric acid (GA) and adipic acid (AA) in N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), 1-Methyl-2-pyrrolidinone (NMP) and sulfolane were determined by using the method of dynamic laser at atmospheric pressure. The experimental SLE data indicates that within the temperature range studied (286.25–358.75 K), the solubilities of SA, GA and AA in above five solvents is proportional to the temperature. Meanwhile, three thermodynamic models (Apelblat model, λh model, the modified nonrandom two liquid (NRTL) activity coefficient model) were used to correlate the experimental data, the results show that the correlated data is generally consistent with the experimental data. The result of Akaike Information Criterion (AIC) analysis filter out the best model for every system. In addition, the thermodynamic functions (dissolution enthalpy, entropy, Gibbs energy) were obtained from the SLE data by calculating the van't Hoff equation.

A highly stable PBI solvent resistant nanofiltration membrane prepared via versatile and simple crosslinking process

A polybenzimidazole (PBI) solvent resistant nanofiltration (SRNF) membrane with super high stability is designed and fabricated by a simple and effective intermolecular cross-linking reaction. There is a dramatic improvement in the solvent stability of the PBI membranes after crosslinking. The membrane keeps stable in even strong apolar solvent like N,N-dimethyl formamide (DMF), N,N-dimethylacetamide (DMAc) after crosslinking. The morphology together with performance can be easily tuned by the polymer concentration. The results indicate that with increasing polymer concentration in cast solution, an increased rejection and a decreased flux are realized. The prepared cross-linked membranes show a rejection of 99% on Rose Bengal (RB) in Ethanol, isopropanol (IPA) and DMF, exhibiting very good prospects in SRNF application. This paper provides a simple and versatile way to create PBI SRNF membranes.

Accuracy Profiles for Analyzing Residual Solvents in Textiles by GC-MS.

Excess residual solvents (RSs) in clothes or other textiles could be toxic and pose risks to both humans and the environment. N,N-Dimethylformamide (DMF), N,N-dimethylacetamide (DMAc) and 1-methyl-2-pyrrolidinone (NMP) are important chemicals frequently used as solvents in the textile industry. Several organizations have proposed limiting DMF, DMAc and NMP in textiles, but an appropriate detection method has not been proposed. A sensitive GC-MS method for the quantification of DMF, DMAc and NMP in textiles was developed. After extraction with ethyl acetate, these RSs were separated on a DB-5MS capillary column. The oven temperature was increased from 50°C (held for 0.5 min) at 10°C/min to 120°C (held for 1 min). The method was fully validated according to the accuracy profile procedure, which is based on β-expectation tolerance intervals for the total measurement bias. Linearity was observed in the range of 0.5-10 mg/L for the solvents with limit of quantification values of 4.2, 3.5 and 2.5 mg/kg for DMF, DMAc and NMP, respectively. The repeatability and intermediate precision were <5.34% and 7.95% for DMF, 5.37% and 9.68% for DMAc, and 2.68% and 5.85% for NMP. The recoveries of DMF, DMAc and NMP were 91.2-106.3%, 89.5-97.7% and 85.6-101.3%, respectively.

Pebax membrane for CO2/CH4 separation: Effects of various solvents on morphology and performance

ABSTRACTIn this study, the effects of different solvents on the morphology and permeation of poly(ether‐block‐amide) (Pebax‐1657) membranes were investigated. Pebax membranes were fabricated via a solution casting method with five different solvents, that is, N,N‐dimethyl formamide (DMF), N,N‐dimethyl acetamide (DMAc), N‐methyl‐2‐pyrrolidone (NMP), formic acid, and a mixture of ethanol (EtOH) with water (H2O). Cross‐sectional scanning electron microscopy analysis of the membranes was performed to investigate the morphology of the prepared membranes. X‐ray diffraction and Fourier transform infrared analysis were also carried out to characterize the membranes. The interactions of the polymer and various solvents were evaluated with Hansen solubility parameters. Permeation experiments for CO2 and CH4 gases were performed to study the effects of the solvents on the permeation properties of the membranes. The solvent properties, such as the molar volume, boiling point, and solubility parameters, were investigated as were the membranes characteristics, such as the crystallinity, d‐spacing, and fractional free volume. The results obtained from the experiments show that the CO2 permeability for the membranes prepared with different solvents followed this order: NMP &gt; DMF &gt; Formic acid &gt; DMAc &gt; H2O/EtOH mixture. With increasing molar volume, the gas permeability increased for all of the membranes, except for DMAc, which showed a lower permeability because of its highly crystalline structure. DMF showed a higher CO2/CH4 ideal selectivity compared to the other membranes and, consequently, could be introduced as the best solvent from all aspects for the Pebax‐1657 membrane. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44531.

Preparation of poly(L-lactic acid) membrane from solvent mixture via immersion precipitation

ABSTRACTPoly (L-lactic acid) (PLLA) membranes were fabricated through immersion precipitation method. 1, 4-dioxane (DX), N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), N, N-dimethyl-acetamide (DMAc), and DX/NMP, DX/DMF and DX/DMAc were used as solvents severally. With a focus on the PLLA/DX/NMP/H2O system, the effect of solvent mixture on PLLA membrane was investigated by altering the ratio of DX/NMP. Various membrane morphologies were obtained, which were further correlated by mean of solubility parameter and viscosity of casting solution. It was found that the membrane cast with DX/NMP (1/1) exhibited ideal structure and better performance compared with membranes cast with same concentration of PLLA.