Pervaporation of aqueous alcohol mixtures through a membrane prepared by grafting of polar monomer onto nylon 4

A hydrophilic pervaporation membrane was prepared via a homografting polymerization of N,N′-(dimethylamino)ethyl methacrylate (DMAEM) onto nylon 4 backbone, DMAEM-g-N4. The water permselectivity was improved by the ammonium quaterization of the pendant N,N′-dimethylamino group on the DMAEM-g-N4 membrane using demethyl sulfate, DMAEMQ-g-N4. The separation factor and permeation rate for both chemically modified nylon 4 membranes were higher than those of the unmodified nylon 4 membrane. The effects of feed composition, feed temperature, and molar volume of the alcohols on pervaporation performance were investigated. Optimum pervaporation was obtained by a DMAEMQ-g-N4 membrane with a degree of grafting of 12.7% for a 90 wt % ethanol feed concentration, giving a separation factor of 36 and a permeation rate of 564 g/m²h. © 1995 John Wiley & Sons, Inc.     

Novel Amine Modifiers for Unsaturated Polyester Resins

The results of studies are presented on the synthesis and functioning of amine modifiers for unsaturated polyester resins obtained by reacting ethylene oxide or propylene oxide with N,N ′‐diphenylethane‐1,2‐diamine and by reacting ethylene oxide with N,N ′‐diphenylhexane‐1,6‐diamine. When used in the amount of up to 2 wt.‐%, the amines substantially (several times) reduced the gelation time of modified unsaturated polyesters. The reactivity of resins was improved in expense of their stability.     

Thermoresponsive and biocompatible poly(vinyl alcohol)‐graft‐poly(N,N‐diethylacrylamide) copolymer: Microwave‐assisted synthesis,characterization, and swelling behavior

Novel thermoresponsive poly(vinyl alcohol)‐graft‐poly(N,N‐diethylacrylamide) (PVA‐g‐PDEAAm) copolymers were prepared by microwave‐assisted graft copolymerization using a potassium persulfate/N,N,N′,N′‐tetramethylethylenediamine (KPS/TEMED) initiator system. The structures of PVA‐g‐PDEAAm copolymers were characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry/thermogravimetric analysis, gel permeation chromatography, X‐ray diffraction, and scanning electron microscopy. The effects of various process parameters on grafting were systematically studied: microwave power, KPS, monomer and PVA concentrations, and ultraviolet irradiation. Under optimal conditions, the maximum grafting percent and graft efficiency were 101% and 93%, respectively. Furthermore, a lower critical temperature of copolymers was measured in the range 29–31 °C by ultraviolet spectroscopy. The swelling behavior of graft membranes was carried out at various temperatures, and the results showed that the swelling behavior of membranes was dependent on the temperature. In vitro cell culture studies using L929 fibroblast cells confirmed cell compatibility with the PVA‐g‐PDEAAm copolymer and its membrane, making them an attractive candidate for drug delivery systems. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45969.     

Characterization of methyl‐substituted polyamides used for reverse osmosis membranes by positron annihilation lifetime spectroscopy and MD simulation

Three kinds of polyamides were synthesized from three diamines and 1,3,5‐benzenetricarbonyl trichloride (TMC). The diamines used were m‐phenylene diamine, N‐methyl‐m‐phenylenediamine, and N,N′‐dimethyl‐m‐phenylenediamine. The average free volume sizes of the polyamides were measured by positron annihilation lifetime spectroscopy (PALS), and the free volume fractions were evaluated by molecular dynamics (MD) simulations. The methyl substitution on amino groups of diamines brought about an increase in interstitial space of molecular chains of the polyamides. In addition, reverse osmosis (RO) membranes were prepared by interfacial polymerization from the three diamines and TMC. The increase in the degree of methyl‐substitution of diamines led to increased chlorine resistance and decreased salt rejections of the polyamide RO membranes. Thus, the methyl‐substitution of diamines significantly influenced membrane performance. The vacancy sizes and fractional volumes in polyamides evaluated by PALS measurement and MD simulation were well correlated with salt rejection of polyamide RO membranes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Quaternized poly (2,6-dimethyl-1,4-phenylene oxide) crosslinked by tertiary amine and siloxane for anion exchange membranes

A series of tertiary amine and siloxane crosslinked composite anion exchange membranes were prepared by incorporating 2-(3,4-epoxycyclohexyl) ethyltrimethoxysilane (EHTMS) and N,N,N′,N′-Tetramethyl-1,6-hexanediamine (TMHDA) into N-Methyldiethanolamine (MDEA)-functionalized poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) backbone via sol-gel process. The resultant membranes named as AEM-X (X = 1, 2, 3, 4), which own a three-dimensional (3D) cross-linking structure, exhibit superior swelling resistance, mechanical properties, even the thermal stability is up to 220°C. Compared with AEM-1 (contains no crosslinker), the swelling ratio of AEM-2 obviously decreases by 10.2% at 80°C, while the OH⁻ conductivity of AEM-2 has a merely 1.9% decline (20.6 mS cm⁻¹) at 80°C and can maintain 67% of its initial value in a 2 M aqueous NaOH at 80°C for 240 h. The simultaneous introduction of inorganic siloxane and organic linear crosslinker provides a new idea for the preparation of anion exchange membranes with largely improvement in dimensional stability and alkali resistance while the ionic conductivity is kept at comparatively high level.     

Carrier Facilitated Transport of Europium(III) Across Supported Liquid Membranes Containing N,N,N′,N′-tetra-2-ethylhexyl-3-oxapentane-diamide (T2EHDGA) as the Extractant

Studies on the solvent extraction and pertraction behavior of europium(III) was carried out from acidic feed solutions using N,N,N′,N′-tetra-2-ethylhexyl-3-oxapentane-diamide (T2EHDGA) in n-dodecane as the solvent. The nature of the extracted species from the solvent extraction studies conformed to Eu(NO₃)₃ · 3T2EHDGA which is in variance with the analogous Eu(III) – TODGA (linear homolog of T2EHDGA) extraction system. The transport behavior of Eu(III) was investigated from a feed containing 3.0 M HNO₃ into a receiver phase containing 0.01 M HNO₃ across a PTFE flat sheet supported liquid membrane (SLM) containing 0.2 M T2EHDGA in n-dodecane as the carrier solvent and 30% iso-decanol as the phase modifier. Effects of feed acidity, carrier extractant concentration, membrane pore size, and Eu concentration in the feed on the transport rates of Eu(III) were also investigated. Membrane diffusion coefficient (D _o) for the pertracted species was calculated using the Wilke-Chang equation as 4.25 × 10^?6 cm² · s^?1. The influence of Eu concentration on the flux was also investigated. The role of temperature on the transport rates was investigated and the thermodynamic parameters were calculated.     

Mathematical Model for the Extraction of Neodymium from Nitrate Media using Hollow Fiber Supported Liquid Membrane Operated in a Recycling Mode

A mathematical model for facilitated extraction of Neodymium (Nd³⁺) ions from nitrate media using microporous hollow fiber supported liquid membrane (HFSLM) operated in a recycling mode is presented. Extractant N,N,N′, N′-tetraoctyl diglycolamide (TODGA) diluted with n-dodecane was used as the membrane phase. Di-n-hexyl octanamide (DHOA) has been used as a phase modifier for the extractant. The model developed is not specific to the case considered and has a more general and wide applicability. The model has been developed using equilibrium-based approach. The complexation and de-complexation reactions were assumed to be fast and at equilibrium. Mass balance equations for both acid (HNO₃) and TODGA were also incorporated in the model. It was observed that the model results are in good agreement with the experimental data when diffusivity of metal-complex (D _m ) and acid-complex (D _hm ) through the membrane phase in the pore is 6 × 10^?12 m²/s and 1.2 × 10^?10 m²/s. Once the values of D _m and D _hm are estimated by simulation for one set of data, there are no further fitting parameters in the model. The model can then be used in a truly predictive mode for all the remaining data sets.     

Water–alcohol separation by pervaporation through poly(amide-sulfonamide)s (PASAs) membranes

Pervaporation membranes derived from seven homopolymers of poly(amide-sulfonamide)s (PASAs) were prepared by casting 10–17% polymer solutions of N,N-dimethylacetamide. The membranes were characterized by sorption experiments, scanning electron microscope, and wide-angle X-ray diffraction. During the pervaporation of 90 wt % aqueous solution of methanol, ethanol, 1-propanol, and 2-propanol, all membranes were preferentially permeable to water, and their separation factors were mainly dependent on the molecular weight of the solvent. The exact structure of the PASAs had a profound effect on their pervaporation characteristics. Polymeric membrane based on N,N′-bis(4-aminophenylsulfonyl)-1,3-diaminopropane and isophthaloyl chloride exhibited the best selectivity factor of 1984 for a 10 : 90 (by weight) mixture of water/ethanol at 20°C. However, the permeation rates of all materials for dehydration of 90 wt % ethanol were slow in a range of 6.6–34.4 g m⁻² h⁻¹. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1113–1119, 1997     

Microwave assisted novel synthetic route for polyfluorenes containing triphenylamine and solubilizing alkyl moiety for blue emitting diodes

A series of blue electroluminescent polyfluorenes (PFs) containing triphenylamine and various alkyl moieties were synthesized using an Ni(0) mediated C?C Yamamoto coupling reaction assisted by microwaves. The synthesized PFs were characterized by various spectroscopic techniques. Their absorption and photoluminescence properties were investigated in solvent and found to possess characteristic electronic absorption and emission spectra. These PFs were found to emit in the blue region (407?415 nm) with high quantum yield in the range 0.41?0.73. Cyclic voltammetry studies of the PFs revealed that the compounds were stable under redox conditions with highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital in the range 5.24–5.29 eV and 1.98?2.01 eV, respectively. The E_HOMO for the PFs was similar to the most widely used hole transporting materials N,N′‐Di(1‐naphthyl)‐N,N′‐diphenyl‐(1,1′‐biphenyl)‐4,4′‐diamine (NPD), N,N′‐Bis(3‐methylphenyl)‐N,N′‐diphenylbenzidine (TPD) and N²,N²,N²′,N²′,N⁷,N⁷,N⁷′,N⁷′‐octakis(4‐methoxyphenyl)‐9,9′‐spirobi[9H‐ fluorene]‐2,2′,7,7′‐tetramine, Spiro‐OMeTAD (spiro‐OMe‐TAD). The thermal stability observed for the PFs accounts for their use under ambient conditions. The electrochemical studies of the fabricated polymer light emitting diodes suggest that the PFs have potential to be used as hole transporting and blue electroluminescent materials for optoelectronic devices. © 2017 Society of Chemical Industry     

Chelate membrane from poly(vinyl alcohol)/poly(N-salicylidene allyl amine) blend. III. Effect of Mn(II) and Co(II) on oxygen/nitrogen separation

Facilitated transport of oxygen through Co(II) and Mn(II) chelate membranes from poly(vinyl alcohol)/poly(N-salicylidene allyl amine) was investigated. As the membranes became chelated, oxygen diffusivity decreased and the solubility toward oxygen was enhanced. The oxygen permeability of the base poly(vinyl alcohol)/poly(N-salicylidene allyl amine) membrane was 2.6 × 10⁻³ cm³(STP)cm/cm² cm Hg sec (barrer), and the selectivity toward oxygen was 2.2. As Co(II) was introduced into this membrane, oxygen permeability and oxygen selectivity increased to 2.82 × 10⁻² barrer and 8.5, respectively. The permeability and selectivity of Mn(II) chelate membrane were 3.28 × 10⁻² and 5, respectively. A major reason for the increased selectivity was the enhanced solubility of oxygen in chelate membrane upon chelation. The transport behavior of chelate membranes followed a dual-mode transport, and the parameters were estimated and compared between Co(II) and Mn(II) membranes. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 483–490, 1997     

PREPARATION AND TESTING OF CARBON/SILICALITE-1 COMPOSITE MEMBRANES

Methods for preparation of carbon/silicalite-1 composite membranes have been developed. First, silicalite-1 membranes were prepared by in-situ hydrothermal synthesis on both porous alumina and metal disks. Preparation of the carbon/silicalite-1 composite membranes was accomplished by polymerizing furfuryl alcohol on the surface of the silicalite-1 membrane, followed by carbonizing the polymer layer in an inert atmosphere at 773 K. The pure silicalite-1 membrane showed no selectivity for single gases, indicating the presence of intercrystalline diffusion and viscous flow as the dominant transport mechanism. The carbon/zeolite composite membrane exhibited ideal selectivities for He/N₂, CO₂/N₂, and N₂/CH₄ of 11.99, 17.12, and 3.58 at room temperature. No permeation of n-butane and i-butane for the composite membrane was detected up to temperatures of 453 K, indicating that the pore size for the composite membrane was approximately 0.4 nm. By carefully oxidizing the carbon layer in air at 623 K, the pore size of the composite membrane was adjusted such that n-butane permeation could be detected. No permeation of i-butane was apparent, suggesting that the pore size of the composite membrane had been enlarged to approximately 0.5 nm. Further oxidation of the carbon layer produced a finite n-/i-C₄H₄ ideal selectivity, indicating that the pore size of the membrane was now larger than 0.55 nm. Therefore, selective oxidation of the carbon layer can be used to control the pore size of the composite membrane.     

Synthesis and properties of polysiloxane containing N,N′-bis(diphenylsilyl)tetraphenylcyclodisilazane

A new kind of polysiloxane containing N,N′-bis(diphenylsilyl)tetraphenylcyclodisilazane was prepared by the anionic polymerization with a “seed solution” as initiator. The synthesis of monomers N,N′-bis(hydroxydiphenylsilyl)tetraphenylcyclodisilazane (BHPTPC), N,N′-bis(chlorodiphenylsilyl)tetraphenylcyclodisilazane (BCPTPC), and 1,3-dichloro-1,1,3,3-tetraphenyldisilazane (DCTPS) are all reported in this study. The synthesized polysiloxane containing N,N′-bis(diphenylsilyl)tetraphenylcyclodisilazane was characterized by ¹H–NMR, ²⁹Si–NMR, gel permeation chromatography (GPC), and intrinsic viscosity. The thermal stability of the polysiloxane was studied by isothermal gravimetric analysis (IGA). The results demonstrated that the synthesized polysiloxane containing N,N′-bis(diphenylsilyl)tetraphenylcyclodisilazane had excellent thermal stability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 929–933, 2001     

Synthesis and properties of organosoluble polyimides based on novel flourene‐ring containing diacetamido‐diamine

A new diacetamido‐diamine monomer, N′‐[7‐(acetyl‐4‐aminoanilino)‐9,9‐dioctylflouren‐2‐yl]‐N′‐4‐aminophenyl) acetamide (ADOAc), with flourene‐based structure was prepared from the reaction of 4‐aminoacetanillide with 2,7‐dibromo‐9,9‐dioctylfluorene in the presence of 10 mol % CuI, 20 mol % N,N′‐dimethylethylene diamine as catalyst and K₂CO₃ as base. Two new flourene‐ring containing polyimides were prepared from the reaction of ADOAc with aromatic dianhydrides such as pyromellitic dianhydride (PMDA) and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) via chemical imidization of poly(amic acid). The new diamine and the related polyimides were characterized by using conventional methods such as FT‐IR, NMR, and elemental analysis. The polyimides obtained from the reaction of ADOAc with PMDA (PIa) and of ADOAc with BTDA (PIb) had inherent viscosity of 0.49 and 0.58 dL/g respectively, and showed excellent solubility in a variety of organic solvents. The polyimides of PIa and PIb showed excellent thermal stability with 10% weight loss in nitrogen atmosphere at temperatures of 418°C and 407°C and T_g of 172°C and 167°C, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Hydrazinium salts as thermally latent initiators in the polymerization of glycidyl phenyl ether

Novel hydrazinium salts, N,N‐dimethyl N‐benzyl N′‐benzyl N′‐benzoyl hydrazinium hexafluoroantimonate (2) and N,N‐dimethyl N‐benzyl N′‐(2‐propyl) N′‐benzoyl hydrazinium hexafluoroantimonate (3) were synthesized from hydrazinium salt (1) with the corresponding alcohol. Their initiator activities were examined in the polymerization of glycidyl phenyl ether (GPE). The polymerization of GPE did not proceed with 2 and 3 below 60 and 100°C but proceeded rapidly above those temperatures, respectively. It was found that 1–3 served as thermally latent initiators in the polymerization of GPE. The initiating species and terminating species were identified as the proton or alkyl cation and aminimide, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1439–1442, 2005     

Polycarbonate/(N,N′-dialicylidene ethylene diamine) cobalt(II) complex membrane for gas separation

A polycarbonate/(N,N′-dialicylidene ethylene diamine) cobalt(II) (cosalen) complexed membrane was prepared by introducing oxygen carrier (cosalen) into polycarbonate for gas separation. With increasing amount of oxygen carrier in the membranes, the selectivity of O₂/N₂ increased and the permeabilities of both O₂ and N₂ decreased. The selectivity of O₂/N₂ decreased with increasing operating temperature. The pure gases sorption measurements indicated that the affinity between oxygen and the membranes was appreciable higher than that of nitrogen. According to the X-ray analysis of the complexed membranes, the decreased gas diffusivities were caused by the increase of the packing density. The selectivity of O₂/N₂ was 15 and oxygen permeability for the cobalt complexed membrane with 3 wt % oxygen carrier was 0.33 barrers at 5°C. Furthermore, a dual mode sorption mechanism was utilized to describe the behavior of gas sorption and permeation through the cobalt complexed membrane. © 1996 John Wiley & Sons, Inc.     

The influence of manufacturing parameters on the properties of macroporous Zirfon<Superscript>®</Superscript> separators

The manufacturing of the macroporous Zirfon^® separator is based on the film casting technique. This film casting technique allows different manufacturing steps to be varied in order to adapt both the composition and the structure of the separator to the specific requirements of the application. The Zirfon^® separators can be used in alkaline electrochemical cells as a replacement of asbestos. At a temperature of 30 °C the ionic resistance of the separator is as low as about 0.01 Ω. Bubble-Point (BP) pressures as high as 1 MPa could be obtained.     

Synthesis of soluble and thermally stable polyimides from 3,5‐diamino‐N‐(4‐(8‐quinolinoxy) phenyl) aniline and various dianhydrides

Three novel polyimides (PIs) having pendent 4‐(quinolin‐8‐yloxy) aniline group were prepared by polycondensation of a new diamine with commercially available tetracarboxylic dianhydrides, such as pyromellitic dianhydride, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride, and bicyclo[2.2.2]‐oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride. These PIs were characterized by FTIR, ¹H NMR, and elemental analysis; they had high yields with inherent viscosities in the range of 0.4–0.5 dl g⁻¹, and exhibited excellent solubility in many organic solvents such as N,N‐dimethyl acetamide, N,N′‐dimethyl formamide, N‐methyl pyrrolidone (NMP), dimethyl sulfoxide, and pyridine. These PIs exhibited glass transition temperatures (T_g) between 250 and 325° C. Their initial decomposition temperatures (T_i) ranged between 270 and 450°C, and 10% weight loss temperature (T₁₀) up to 500°C with 68% char yield at 600°C under nitrogen atmosphere. Transparent and hard polymer films were obtained via casting from their NMP solutions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and Evaluation of New Anionic Gemini Dispersants as Oil Dispersants to Treat Crude Oil Spill Pollution

Floating petroleum oil spills on the marine ecosystem are generally associated with an escalation of serious environmental problems. This research aimed to synthesis five water-soluble anionic Gemini dispersants to minimize the effect of floating petroleum oil spills on the marine ecosystem. Referring to the spacer type, these dispersant are classified into two categories: the first category is the three acyl amine Gemini dispersants of N,N′- diacyl, (distearoyl-, dipalmitoy-, and dimyristoyl-) N,N-′ sodium 2-hydroxy 3-propane sulfonate propane 1,3 diamine, denoted S, P, and M, and the second category is two alkyl amine Gemini dispersants of N,N′dialkyl -(dicetyl-, and dilauryl-) N,N′-sodium 2-hydroxy 3-propane sulfonate propane 1,3 diamine, denoted C and L. Fourier transform infrared and ¹H NMR spectroscopy, gel permeation chromatography, and elemental analysis were used to verify the chemical formula of the synthesized dispersants. The effectiveness of the synthesized dispersants was investigated as regards their dynamic interfacial tension, carbon–chain length, and hydrophilic–lipophilic balance. The dispersion efficiency of the synthesized dispersant was detected qualitatively and quantitatively using the screen test and Warren Spring Laboratory methods, respectively. Experimental outcomes showed that the maximum dispersion efficiency of 94.7 wt% was achieved by dispersant C at a dispersant\oil ratio of 1:20 at 25°C.     

Liquid–Liquid Extraction of Silver From Chloride Media by N,N′-Tetrasubstituted Dithiomalonamide Derivatives

N,N′-dimethyl-N,N′-diphenyldithiomalonamide (DMDPHDTMA) and N,N′-dimethyl-N,N′-dicyclohexyldithiomalonamide (DMDCHDTMA) were synthesized and tested as extractants for silver in chloride solutions. Even when relatively low concentrations are used, both compounds effectively extract Ag(I) from 2–5 M chloride concentrated aqueous phases. Ag(I) is successfully stripped by a stabilized sodium thiosulfate solution. Results obtained from sequential cycles of extraction-stripping suggest that both extractants exhibit a high Ag(I) loading capacity. The effects of the equilibration time, concentrations of extractant, chloride and hydrogen ions on Ag(I) extraction have been investigated. The chemical reactions involved on Ag(I) extraction are proposed. There is no selectivity of DMDPHDTMA or DMDCHDTMA for Ag(I) when Cu(II) and Fe(III) co-exist in the chloride aqueous solution.     

Structure–stability correlation of copolyimide membranes derived from aliphatic/alicyclic/aromatic diamine and aromatic dianhydrides

New polyamic acids with ‐A‐B‐A‐C‐ type periodic sequence of monomeric units (A derived from a diamine, B from benzophenone‐3,3′,4,4′‐tetracarboxylic dianhydride, and C from benzene‐1,2,4,5‐tetracarboxylic dianhydride) are prepared and transformed into polyimide membranes that are examined by various methods in order to investigate the influence of diamine units (aliphatic, alicyclic, or aromatic) on the morphology, thermal stability, and mechanical properties of membranes. Small‐ and wide‐angle X‐ray scattering and Atomic force microscopy show amorphous character of all membranes except for those containing hexane‐1,6‐diamine units. Thermogravimetric analysis reveals a decrease in the initial decomposition temperature from 551/501 °C to 437/395 °C (for N₂/O₂ atmosphere) when going from membranes with aromatic to those with aliphatic diamine units. Dynamic mechanical analysis shows quite high initial storage modulus (2100–3300 MPa) for all membranes at frequencies of 1, 10, and 20 Hz. The properties of prepared copolymeric polyimide are promising for a wide range of their potential technological applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45227.