Synthesis,characterization and investigation of proton exchange properties of sulfonated polytriazoles from a new semifluorinated diazide monomer

This work describes the synthesis and characterization of a new series of semifluorinated sulfonated polytriazole copolymers (PTATSH‐XX) with varying degree of sulfonation and higher IEC. The copolymers have been prepared by click reaction using a combination of diazide monomers; a newly synthesized diazide monomer namely 4,4‐bis[3‐trifluoromethyl‐4(4‐azidophenoxy)phenyl]benzene (TAZ) and a commercially available diazide monomer namely 4,4′‐diazido‐2,2′‐stilbenedisulfonic acid disodium salt (DADSDB) with a bis‐alkyne monomer namely 4,4′‐(propane‐2,2‐diyl)bis((prop‐2‐ynyloxy)benzene) (BPEBPA). The copolymers are well characterized by FTIR and NMR spectroscopy and have exhibited good solubility and film forming abilities along with good thermal and chemical stability, low water uptake, good dimensional stability and high mechanical properties. The TEM micrographs of the copolymer membranes show good phase separated morphology with cluster size in the range 10–60 nm. The proton conductivity values of the copolymer membranes are found in the range of 15–90 mS cm^?1 at 80°C and 16–97 mS cm^?1 at 90°C. POLYM. ENG. SCI., 57:312–323, 2017. © 2016 Society of Plastics Engineers     

Synthesis and characterization of some aromatic polyphosphonates

Novel aromatic polyphosphonates are synthesized by polycondensation of chloromethyl (methyl, phenyl) phosphonic dichloride with bisphenols using three procedures: melt, solution, and phase transfer catalysis. The molecular weights and spectral characteristics are presented. Mixtures of the polyphosphonates with polyacrylonitrile and nylon 66 are compatible only when the chloromethyl group is present. Eight percent of polyphosphonate in the mixture confers flame resistance to the polymers.     

Synthesis and characterization of some aromatic polyimides

The diamine 2‐methyl‐1,3‐bis(4‐aminophenyloxy)benzene was prepared via a nucleophilic substitution reaction and was characterized with Fourier transform infrared, elemental analysis, and ¹H‐ and ¹³C‐NMR spectroscopy. The prepared diamine was also characterized with single‐crystal analysis. The geometric parameters of C₁₉H₁₈N₂O₂ were in the usual ranges. The dihedral angles between the central phenyl ring and the two terminal aromatic rings were 88.9 and 91.6°. The crystal structure was stabilized by N? H···N hydrogen bonds. The diamine was then polymerized with 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride, 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 3,4,9,10‐perylenetetracarboxylic acid dianhydride, and pyromellitic dianhydride by either a one‐step solution polymerization reaction or a two‐step procedure. These polymers had inherent viscosities ranging from 0.61 to 0.85 dL/gm. Some of the polymers were soluble in most common organic solvents even at room temperature, and some were soluble on heating. The degradation temperatures of the resultant polymers fell in the range of 260–500°C in nitrogen (with only 10% weight loss). The specific heat capacity at 200°C ranged from 1.0 to 2.21 J g^?1 K^?1. The temperatures at which the maximum degradation of the polymer occurred ranged from 510 to 610°C. The glass‐transition temperatures of the polyimides ranged from 182 to 191°C. The activation energy and enthalpy of the polyimides ranged from 44.44 to 73.91 kJ/mol and from 42.58 to 72.08 kJ/mol K, respectively. The moisture absorption was found in the range of 0.23–0.71%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of some new aromatic polyoxadiazoles through cyclodehydration of polyhydrazides

A series of new polyhydrazides containing pyridine heterocyclic ring, bearing bulky aromatic pendent groups, were synthesized from the reaction of diacid chlorides with dihydrazides via low-temperature solution polycondensation. All the polymers were readily soluble in polar solvents such as N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc), and 1-methyl-2-pyrrolidone (NMP) and showed inherent viscosities equal to 0.38–0.68 dL/g. They indicated glass transition temperatures (T _g) ranging from 190 to 220 °C. Polyhydrazides were subjected to cyclodehydration to prepare poly(1,3,4-oxadiazole)s either by thermally or chemically cyclodehydration approximately in the region of 150–320 °C. The poly(1,3,4-oxadiazole)s, made by chemically cyclodehydration exhibited T _gs of 220–250 °C and inherent viscosities equal to 0.38–0.62 dL/g, while the PODs made via thermally cyclodehydration of polyhydrazides did not show any glass transition and exhibited inherent viscosities equal to 0.39–0.66 dL/g. The former polymers were soluble in conc. H₂SO₄ and partially soluble in hot DMF, NMP, DMSO, and DMAc, and the latter were only soluble in conc. H₂SO₄. They had useful levels of thermal stability and were stable up to 450 °C in nitrogen. The structure of polymers was fully characterized by IR and NMR spectroscopies.     

Synthesis and characterization of new ion-exchange membranes

The synthesis of grafted polymers of polyethylene (PE) with acrylic acid and N,N-dimethylamino-2 ethyl acrylate is performed in two steps. The first one needed the ozonization of powder of PE in well-defined conditions to obtain an expected activation. The second one consisted in bulk grafting the two monomers by thermal decomposition of the above hydroperoxides and peroxides of the activated PE. After elimination of homoacrylated by selective solubilization, we obtained films by pressing the copolymers either alone or the mixture of the two copolymers to prepare the anion (or cation) exchange membrane and the amphoteric ion-exchange membrane. The second part of the study deals with the physicochemical characterization of these membranes: thickness, exchange capacity, electrical resistance, transport number, and water content. These characteristics are given for various concentrations of equilibrating solutions and for various pH. The results show that we have perfectly corrected membranes that are competitive with the commercial ones.     

Synthesis and characterization of some new polyurethaneoximes

Two new polyurethaneoximes containing double and triple bonds in the main chain were prepared. An in situ preparation of 2-butene-1,4-diisocyanate and 2-butyne-1,4-diisocyanate and their polycondensation with dimethylglyoxime yielded polymers of low molecular weight. The UV, IR, NMR, DSC and TGA analyses of these polymers are reported. The possible mechanism of thermal degradation of one of the polymers is discussed.     

Sulfonated aromatic hydrocarbon polymers as proton exchange membranes for fuel cells

This article reviews recent studies on proton exchange membrane (PEM) materials for polymer electrolyte fuel cells. In particular, it focuses on the development of novel sulfonated aromatic hydrocarbon polymers for PEMs as alternatives to conventional perfluorinated polymers. It is necessary to improve proton conductivity especially under low-humidity conditions at high operating temperatures to breakthrough the current aromatic PEM system. Capable strategies involve the formation of well-connected proton channels by microphase separation between hydrophilic and hydrophobic domains and the increase of the ion exchange capacity of PEMs while keeping water resistance. Herein, we introduce novel molecular designs of sulfonated aromatic hydrocarbon polymers and their performance as PEMs.     

Chlorination and oxidation of aromatic polyamides. I. Synthesis and characterization of some aromatic polyamides

The synthesis is described of some aromatic polyamides based on unsubstituted, and methyl-, carboxy-, and sulfo-substituted diamines by interfacial polycondensation. Some of them are crosslinked and some of them contain heterocyclic aromatic rings. Their chemical structures are characterized by IR and ¹³C solid-state NMR spectra and the spectra are interpreted. © 1996 John Wiley & Sons, Inc.     

一种新型磺化聚酰亚胺质子交换膜的合成与表征

质子交换膜是质子交换膜燃料电池膜电极的核心部件之一,它的性能好坏对整个系统的运行起着至关重要的作用．目前在质子交换膜燃料电池中普遍采用的质子交换膜材料是全氟磺酸系列薄膜,这类材料具有较高的质子传导率、化学及机械稳定性,但用于直接甲醇燃料电池（DMFC）时则存在甲醇渗透、导致燃料电池输出性能大大降低的问题     

Synthesis and characterization of new aromatic polyesters containing pendent naphthyl units

Two bisphenols, viz., 4,4′‐[1‐(2‐naphthalenyl)ethylidene]bisphenol and 4,4′‐[1‐(2‐naphthalenyl) ethylidene]bis‐3‐methylphenol were prepared by condensation of commercially available 2‐acetonaphthanone with phenol and o‐cresol, respectively. A series of new aromatic polyesters containing pendent naphthyl units was synthesized by phase‐transfer‐catalyzed interfacial polycondensation of these bisphenols with isophthaloyl chloride, terephthaloyl chloride, and a mixture of isophthaloyl chloride/terephthaloyl chloride (50 : 50 mol %). Inherent viscosities of polyesters were in the range 0.83–1.76 dL g⁻¹, while number average molecular weights (M_n) were in the range 61,000–235,000 g mol⁻¹. Polyesters were readily soluble in organic solvents such as dichloromethane, chloroform, tetrahydrofuran, m‐cresol, pyridine, N,N‐dimethylformamide, N,N‐dimethylacetamide, and 1‐methyl‐2‐pyrrolidinone at room temperature. Tough, transparent, and flexible films were cast from a solution of polyesters in chloroform. X‐Ray diffraction measurements displayed a broad halo at 2θ ≅ 19° indicating the amorphous nature of polyesters. Glass transition temperatures of polyesters were in the range 209–259°C. The temperature at 10% weight loss (T₁₀), determined by TGA in nitrogen atmosphere, of polyesters was in the range 435–500°C indicating their good thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

全钒液流电池用质子传导膜研究进展

全钒液流电池(VRB)作为一种大规模蓄电储能装备,在可再生能源发电和节能技术领域将发挥重要作用。质子传导膜是VRB中的关键材料之一,其作用主要有两方面:传导质子连通电堆内电路;阻止正负极电解液间不同价态钒离子的相互渗透,避免能量损失。质子传导膜性能对电池效率和成本有重要影响。在分析VRB基本原理基础上,阐明质子传导膜需同时满足优良的导电性、阻钒性、稳定性和合理成本等要求。以高分子膜的化学组成与物理结构的演化过程为线索,分别论述三类膜材料,包括Nafion系列膜、非全氟型质子传导膜、纳米尺度孔径的多孔膜。在归纳现有膜材料化学结构、物理性质与电学性能的基础上,阐述高性能质子传导膜的重点研究方向与发展前景。     

Synthesis of proton conductive membranes based on inorganic–organic hybrid structure bound with phosphonic acid

Proton conductive inorganic–organic hybrid membranes were synthesized from styrene derivatives of alkoxysilane and ethyl 2-[3-(dihydroxyphosphonyl)-2-oxopropyl] acrylate (EPA) through copolymerization followed by sol–gel reaction. Self-standing, homogeneous and transparent hybrid membranes with chemically bound phosphonic acid groups were synthesized. FT-IR analysis exhibited the hybrid membranes included phosphonic acid groups. ¹³C and ²⁹Si NMR studies indicated that alkoxysilyl functionalized styrene derivatives were not only copolymerized with EPA but also condensed yielding Si–O–Si linkages by sol–gel reaction. TG–DTA analysis revealed that these membranes were thermally stable up to 200 °C in dry O₂. The proton conductivities of the hybrid membranes increased with phosphonic acid content and temperature. The P/Si ratio of the membrane was dependent on the number of alkoxy group in the starting alkoxysilane. The hybrid membrane from (dimethylmethoxysilylmethyl)styrene (DMMSMS(M))/EPA = 1/6 revealed proton conductivities of 6.3 × 10⁻³ and 2.4 × 10⁻⁴ S cm⁻¹ at 68.0% relative humidity and 18.8% relative humidity, respectively, at 140 °C.     

Synthesis and characterization of some new chelating amphoteric ion-exchange resins

Some new chelating amphoteric ion exchange resins have been synthesized by condensing catechol, 8-hydroxyquinoline, hydroquinone, salicyclic acid, sulfosalicyclic acid, 3-hydroxy-2-naphthoic acid, p-hydroxybenzoic acid, β-resorcylic acid, and anthranilic acid with epichlorohydrin employing diethylenetriamine as a cross linking agent in a nonaqueous medium, toluene. These resins are characterized by their physicochemical properties such as moisture retention ability, true density, apparent density, void fraction, concentration of ionogenic groups, volume capacity, total ion exchange capacity, copper exchange capacity, rate of ion exchange, pH titration curves, apparent pK_a and pK_b values, isoionic point values, oxidative degradation, thermal stability, the effect of temperature of equilibration on the capacity of the resin, swelling behavior in various solvents, and absorption specificity towards certain bivalent metal cations in ammonium acetate–dimethylformamide media.     

Synthesis and characterization of a new type of sulfonated poly(ether ether ketone ketone)s for proton exchange membranes

A novel series of sulfonated poly(ether ether ketone ketone)s (SPEEKKs) were prepared by aromatic nucleophilic polycondensation with different ratios of 1,3‐bis(3‐sodium sulfonate‐4‐fluorobenzoyl)benzene to 1,3‐bis(4‐fluorobenzoyl)benzene. ¹H‐NMR spectroscopy was used to confirm the degrees of sulfonation (DS) of the polymers. Thermal stabilities of the SPEEKKs in acid form were characterized by thermogravimetric analysis (TGA), which showed that SPEEKKs were excellently thermally stable at high temperatures. SPEEKK polymers can be easily cast into tough membranes. Both of proton conductivity and methanol diffusion coefficient have been tested in this article. Other properties of the SPEEKK membranes were investigated in detail. The results show that the SPEEKK membranes are promising in proton exchange membrane fuel cells (PEMFCs) application. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of new aromatic poly(ether ketone)s

A general method for the preparation of aromatic poly(ether ketone)s containing amide, amide-imide, cyano, oxadiazole, and pyridazine moieties has been developed. Polymerization is based on a ketone-activated halide displacement from amide-, amide-, imide-, cyano-, oxadiazole-, or pyridazine-containing bis(4-fluorobenzoyl) moieties by bisphenoxides in a polar aprotic solvent. The bis(4-fluorobenzoyl) moieties were prepared by reaction of 4-fluorobenzoyl chloride with diphenoxy monomers containing amide, amide-imide, cyano, oxadiazole, or pyridazine groups under modified Friedel–Crafts conditions in methylene chloride. All of the polyether ketones prepared were amorphous and exhibited T_gs ranging from 134 to 218°C. In addition, films of the aromatic polyether ketones displayed good thermal stability and flexibility. The dielectric constants of the films were characterized as a function of relative humidity (RH). © 1995 John Wiley & Sons, Inc.     

Synthesis and characterization of new fluorinated aromatic polyesters containing trifluoromethylphenoxy pendant groups

A series of novel fluorinated aromatic polyesters containing trifluoromethylphenoxy pendant groups was synthesized by interfacial polycondensation of 2‐(4‐trifluoromethylphenoxy)terephthalyl chloride with various bisphenols in dichloromethane. The polyesters obtained in good yields had weight‐average molecular weights of 70,600–29,800 g/mol, polydispersities of 1.81–2.08, and were all amorphous. All polyesters were easily soluble in organic solvents such as N,N‐dimethylformamide, tetrahydrofuran, o‐chlorophenol, pyridine, and dichloromethane. These fluorinated polyesters showed glass transition temperature of 133–210°C, and good thermal stability with almost no weight loss up to 378°C, the 10% weight loss temperature of 472–523°C as well as char yield of 32–63% at 600°C in nitrogen. These polyester films cast from chloroform solutions exhibited tensile strengths ranging from 102 to 126 MPa, elongation at break from 6.3% to 11.7%, and tensile moduli from 2.1 to 3.3 GPa. The resulting polyester films also displayed low dielectric constants between 2.18 and 2.49 (1 MHz), high transparency with an ultraviolet‐visible absorption cut‐off wavelengths in the 332–355 nm range, and excellent electric strengths (50.4–65.6 kV/mm) and volume resistivity (2.51–6.03 × 10¹⁶ Ω cm). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of new sulfonated copolytriazoles and their proton exchange membrane properties

This work reports the synthesis and characterization of a series of new sulfonated copolytriazoles. The polymers were prepared by CuI catalyzed 1,3-cycloaddition reaction of an equimolar amount of a dialkyne monomer, 1,3-diethynylbenzene and a mixture of two diazide monomers, namely, 4,4′-diazidodiphenyl ether and 4,4′-diazido-2,2′-stilbenedisulfonic acid disodium salt. The copolymers showed high inherent viscosity indicating the formation of high molar mass product. The copolymers were characterized by Fourier transform infrared and proton nuclear magnetic resonance spectroscopic techniques. The copolymer membranes displayed moderate water uptake, high dimensional, mechanical, and thermal stability. Transmission electron microscopy micrographs displayed excellent phase-separated morphology along with very fine ionic clusters. The copolymer PTEOSH-90 (90% degree of sulfonation) showed much higher proton conductivity value which is up to 196 mS cm⁻¹ at 80 °C in completely hydrated condition compared to that of Nafion (165 mS cm⁻¹). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48514.     

Synthesis and characterization of polyethersulfone membranes

Phase inversion method was used to prepare polyethersulfone (PES) ultrafiltration (UF) membranes. Polyethylene glycol (PEG); N, N-dimethyl formamide (DMF) and water were utilized as pore-forming additive, solvent and non-solvent, respectively. Effects of PES and PEG concentrations in the casting solution, PEG molecular weight (MW) and coagulation bath temperature (CBT) on morphology of the prepared membranes were investigated. Taguchi experimental design was applied to run a minimum number of experiments. 18 membranes were synthesized and their permeation and rejection properties to pure water and human serum albumin (HSA) solution were studied. It was found out that increasing PEG concentration, PEG MW and CBT, accelerates diffusional exchange rate of solvent (DMF) and non-solvent (water) and consequently facilitates formation of macrovoids in the membrane structure. The results showed that, increasing PES concentration, however, slows down the demixing process. This prevents instantaneous growth of nucleuses in the membrane structure. Hence, a large number of small nucleuses are created and distributed throughout the polymer film and denser membranes are synthesized. A trade-off between water permeation and HSA rejection was involved, with membranes having higher water permeation exhibited lower HSA rejection, and vice versa. Hence, optimizing preparation variables to achieve high pure water permeation flux along with reasonable HSA rejection was inevitable. Analysis of variance (ANOVA) showed that all parameters have significant effects on the response (water flux and HSA rejection). However, CBT and PES concentration were more influential factors than PEG concentration and MW on the responses.     

Physicochemical characterization of some fully aromatic polyamides

The characterization of eight fully aromatic polyamides are described with the procedures required to yield film- and fiber-forming materials. Solutions of these aromatic polyamides in dimethylacetamide were characterized by NMR and the effects of dissolved lithium chloride on these spectra investigated. The NMR resonances for specific protons in these polymers are assigned. The IR spectra of thin films and fibers of these polyamides are also reported, together with glass transition temperatures as measured by differential scanning calorimetry (DSC). The value of NMR and IR to identify specific polyamide homopolymers and copolymers is discussed.