Solubility In Dimethyl Sulfoxide Research Articles

Study of the physico-chemical properties of oligoephiramides based on 4-aminobenzoic acid

This work was carried out to obtain a number of aromatic oligoetheramides and to evaluate the effect of their structure on mesomorphic and thermal properties. Oligoetheramides based on 4-aminobenzoic acid (4-ABA) were synthesized by hightemperature polycondensation. The structure of the obtained compounds was identified by IR spectroscopy, the thermal parameters were determined from the data of thermogravimetric analysis (TGA), the phase transition temperatures were determined by differential scanning calorimetry (DSC), and the manifestation of the optical activity of oligoetheramide solutions was studied by optical polarization microscopy (OPM). It was revealed that the samples dissolve when heated in sulfuric acid, in dimethylformamide (DMF), dimethylacetamide (DMAA) and have limited solubility in dimethylsulfoxide (DMSO). Solutions of oligomers exhibited optical activity at crossed microscope polarizers.

Production of water‐soluble sulfated exopolysaccharide with anticancer activity from Anoxybacillus gonensisYK25

AbstractBACKGROUNDThermophilic bacteria are accepted as novel sources of exopolysaccharides (EPSs) with different biological activities. This study was conducted to test EPS production potential of thermophilic bacteria isolated from hot springs in Erzurum province (Turkey), to optimize EPS production from the best isolate in molasses medium, to characterize the produced EPS, and to investigate its anticancer activity.RESULTSAmong 28 isolates, the best EPS producer isolate was found to be Anoxybacillus gonensis YK25 (GenBank No: MN865832). Under optimized culture conditions (initial pH 7.0, temperature 55 °C, molasses concentration 100 mL/L, peptone concentration 6 g/L, and incubation time 96 h), 4.4 g/L EPS was produced. Molecular weight of EPS was 102 kDa. Carbohydrate and protein contents of EPS were 91.4% and 4.1%, respectively. EPS was a heteropolysaccharide containing xylose (59%), sucrose (18%), glucose (16%), and galactose (5%). It had a high solubility in water and a moderate solubility in dimethyl sulfoxide (DMSO), but it was insoluble in polar solvents. FTIR analysis confirmed the presence of hydroxyl, carboxyl, amide, and sulphate groups. EPS showed anticancer activity against SHSY‐5Y, HT‐29, DU‐145, and A‐549 cell lines in a dose‐dependent manner. The IC50 values of EPS for A‐549, DU‐145, SHSY‐5Y, and HT‐29 cancer cells were 5.5, 9.61, 15.62, and 17.35 mg/mL, respectively.CONCLUSIONThe EPS production potential of A. gonensis, and the anticancer activity of the produced EPS were revealed. Furthermore, it was shown for the first time that the main monomer of bacterial heteropolysaccharides would be xylose. This study indicates that Anoxybacillus species may be a novel source of pharmaceutically‐important EPSs. © 2020 Society of Chemical Industry

Temperature dependence of sulfur solubility in dimethyl sulfoxide and changes in concentration of supersaturated sulfur solutions at 25 °C

This is the first systematic study on the isothermal dependence of the solubility of rhombic sulfur in dimethyl sulfoxide at a temperature range of 298–448 K (25–175 °C) using a gravity method. It was found that sulfur solubility is affected not only by the temperature of the solvent, but also by the phase transition of sulfur to monoclinic modification occurring during the dissolution process, as well as by the melting of the rhombic phase of sulfur. It was shown that the concentration of a supersaturated sulfur solution in dimethyl sulfoxide under standard states, obtained by cooling isothermally heated solutions to 298 K (25 °C), increases significantly as the temperature of the isotherm rises, which contrasts with the findings available in the existing literature. Key aspects of sulfur solubility in DMSO are considered.

Alkaline stability of ether bond free fluorene-based anion exchange polymer containing cycloaliphatic quaternary ammonium groups

Quaternary piperidinium cation was incorporated into aryl-ether-bond-free fluorene-based polymer by flexible alkyl side chains to synthesize a highly conductive and chemically stable anion exchange membrane (AEM). The membrane of the OH− form shows good solubility in dimethyl sulfoxide and methanol but not soluble in water. In a fully hydrated state, the OH− conductivity reached 58 mS cm−1 at 80 °C. The results of 1H NMR spectra revealed that the alkyl-substituted N-methylpiperidinium cationic group was excellent alkaline stable as only 13% cationic group was degraded after 168 h storage in 1 M NaOH solution at 80 °C.

Synthesis of glycolide by catalytic depolymerization of glycolic acid oligomers modified by polyhydric alcohols

Polymers based on lactide and glycolide are widely used in medicine and pharmaceutics. Glycolide is one of initial monomer for lactide-glycolide copolymers obtainment and its purity has a great significance for production of such polymers with high molecular weight. This research is devoted to the synthesis of glycolide by depolymerization of glycolic acid oligomers modified by polyhydric alcohols in the presence of magnesium, zinc and tin (IV) oxides as the catalysts. Modification of glycolic acid oligomers by polyhydric alcohols allow controlling their molecular weight and decreasing crystallinity degree that affect the oligomers solubility in dimethyl sulfoxide and the yield and purity of target glycolide. Modification of glycolic acid oligomers by polyhydric alcohols results in increasing the yield by 5-10 % and achieving the purity of monomers by 99.0 % in comparison with synthesis from unmodified oligomers. To determine glycolide content in samples, gas chromatography using acetonitrile and hexafluoroisopropanol as solvents was carried out.

Highly bright and stable all-inorganic perovskite light-emitting diodes with methoxypolyethylene glycols modified CsPbBr3 emission layer

Modifying the inorganic perovskite emission layer (EML) with polymer materials is one of the key strategies to improve the performance of perovskite light-emitting diodes (PeLEDs). However, the reported polymers, such as polyethylene glycol (PEG), typically have poor solubility in solvents [like dimethylsulfoxide (DMSO)] of perovskite precursors, which requires a pre-heating process to dissolve them. Here, methoxypolyethylene glycol (mPEG), which possesses high solubility in DMSO, is introduced into the perovskite precursors without pre-heating. The highest luminance of 33 500 cd m−2 and the maximum current efficiency of 3.14 cd A−1 are achieved in the prepared PeLED by optimizing the mPEG content in the CsPbBr3 EML, which are even better than those of the PeLEDs modified with PEG. Moreover, the optimized PeLED shows a sub-bandgap turn-on voltage of 2.3 V, which is among the lowest values of single polymer-assisted all-inorganic PeLEDs. The device stability of PeLEDs is also improved by mPEG doping in the CsPbBr3 EML, which shows no obvious decay after operating at an initial luminance of 100 cd m−2 for more than 150 min and 24 h for bare and encapsulated devices, respectively. Our work reveals the great potential of the polymer, mPEG, in modifying the CsPbBr3 EML film for highly bright and stable PeLEDs.

Organic solvents-soluble zinc(II) and cadmium(II) complexes based on 2-aryl substituted-8-hydroxyquinoline: Synthesis, crystal structures, photoluminescence, thermal and theoretical studies

Two novel C-2 position modified 8-hydroxyquinoline ligands, (E)-2-[(4-tert-butylphenyl)ethenyl]-8-hydroxyquinoline (L1) and (E)-2-[(2-chloro-3,4-dimethoxyphenyl)ethenyl]-8-hydroxyquinoline (L2) as well as their zinc(II) and cadmium(II) complexes, namely Zn2(L1)4, Cd3(L1)6, Zn3(L2)6 and Cd3(L2)6 were designed and synthesized. Thanks to the introduction of aromatic tert-butyl and methoxy, ligands L1 and L2 are highly soluble and complexes are having good solubility in dimethyl sulfoxide (DMSO) and chloroform. X-ray structural analysis indicate four complexes were in P21/c, P2/c, P1¯, C2/c space group, respectively, and exhibit a monoclinic crystal system except Zn3(L2)6, which hold a triclinic crystal system. Structural formulea and coordinating behavior of these complexes were also investigated by NMR, UV–Vis and fluorescence spectroscopic titrations in solution, revealing four complexes were well coordinated. Solid state photoluminescence studies reveal they emit strong yellow-orange luminescence at 568–612 nm with 5.47–11.79 ns lifetime. Thermogravimetric and theoretical electronic structure analysis indicate that four complexes appear to be promising candidates for the application as yellow luminescent materials.

Mechanistic Insights into Oxygen Reduction and Evolution Reactions in Non-Aqueous Metal-Air Batteries

Non-aqueous metal-air batteries have generated strong research interest because they possess much greater theoretical gravimetric energy storage density than today’s rechargeable battery technologies.1-4 This has re-kindled research into the fundamentals of oxygen reduction and evolution reactions (ORR and OER) in non-aqueous electrolytes because they are the central electrochemical processes at metal-air cathodes. Understanding the reaction mechanisms is critical to improving cycling efficiency and making rechargeable metal-air batteries a reality. We will present the results of a series of electrochemical studies of the ORR/OER on a gold electrode in strictly dry, non-aqueous dimethyl sulfoxide (DMSO) electrolytes containing different cations, including H+, Li+, and Na+,5,6 using in situ spectroelectrochemistry and first-principles calculations and theoretical modeling. Significantly the ORRs share a common characteristic, namely the superoxide anion (O2 -), the one-electron reduction product of O2, is the first O2 reduction product to form. It has several important consequences: O2 - thus controls the onset potential of the ORR, and its solubility in the electrolyte makes solution-phase reactions involving O2 - an integral part of the electrode processes at low overpotentials, including the formation of superoxides and peroxides (via disproportionation of the superoxides) away from the cathode. On the other hand, there is a clear contrast between Li+ and Na+: Whereas the main reduction product is Li2O2 for Li+, which requires a high overpotential to be oxidized, the reduction product for Na+ is predominantly NaO2, whose high solubility in DMSO alleviates solid buildup on the electrode and also facilitates the oxidation of NaO2. Consequently the Na+ O2 cathode is much more reversible than its Li+ counterpart. The energetic factors controlling the formation of O2 -, solution vs. surface reaction pathways, and the lack of Na2O2 formation will be discussed. Overall, our studies reveal that the ORR/OER mechanisms depend intimately on the cation, potential, and electrolyte, and contribute new mechanistic understanding to the eventual realization of reversible metal-air battery technologies. 1. P.G. Bruce, S.A. Freunberger, L.J. Hardwick, J.-M. Tarascon, Nat. Mater. 2012, 11, 19. 2. J. Lu, L. Li, J.-B. Park, Y.-K. Sun, F. Wu, K. Amine, Chem. Rev. 2014, 114, 5611. 3. A.C. Luntz, B.D. McCloskey, Chem. Rev. 2014 , 114, 11721. 4. R. Black, B. Adams, L.F. Nazar, Adv. Energy Mater. 2012, 2, 801 5. Z. Peng, Y. Chen, P.G. Bruce, Y. Xu, Angew. Chem. Int. Ed. 2015, 54, 8165. 6. Y. Zhang, X. Zhang, J. Wang, W.C. McKee, Y. Xu, Z. Peng, J. Phys. Chem. C 2016, 120, 3690.

Experimental solubility of hydrogen sulfide and carbon dioxide in dimethylformamide and dimethylsulfoxide

The solubility of hydrogen sulfide and carbondioxide in dimethylsulfoxide and dimethylformamide were experimentally measured. Gas concentrations were systematically measured by isochoric saturation method at temperatures from 303.15 to 353.15K and pressure from vapor pressure of solvent up to about 2.0MPa. Results show that H2S dissolves more than CO2 in both solvents, and that chemical dissolution has significant role in H2S solubility in dimethylsulfoxide. The experimental data were correlated by using: (1) a model comprised of the extended Henry's law and Pitzer's virial expansion for the excess Gibbs energy, and (2) a generic Redlich–Kwong (RK) cubic equation of state.

Synthesis and Characterization of Perfluorooctanoic Acid Anionic Surfactant Doped Nanosize Polyaniline

Surfactant doped polyaniline was synthesized in the aqueous solution of aniline and anionic surfactant of perfluorooctanoic acid (PFO) by chemical synthesis using potassium peroxy disulphate as an oxidant by varying the aniline to surfactant ratio. The solubility of the chemically prepared surfactant doped polyaniline (PANI) was ascertained and it showed good solubility in dimethyl sulfoxide (DMSO), dimethylformamide (DMF), acetone, acetonitrile, ethanol, aceticacid, trichloroethylene, dichloromethane, tetrahydrofuran, ethylacetate, diethylether, toluene, chloroform and sparingly soluble in n-hexane and water. The prepared polymers were characterized by fourier transform infrared spectroscopy (FTIR), UV-visible, X-ray diffraction (XRD), cyclic voltammetric (CV), EIS and scanning electron microscopy (SEM). The analysis of UV-visible and FTIR showed that aniline has been polymerized to PANI in its conducting emeraldine form. FTIR spectra showed that the peaks at 1670, 3315 and 1400 cm-1 corresponded to PFO. FTIR spectra showed that amine peak observed at 1593 cm-1 was shifted to lower wave number due to the interaction between PANI and the surfactant. SEM analysis showed that the variation in morphology of doped PANI was predominantly dependent on the concentration of the surfactant. Elemental analysis was done by energy dispersive spectroscopic (EDAX) which shows the presence of C, N, O, S and F. XRD pattern showed that the formation of nanosized (18 nm) and crystalline polymer. CV studies of the synthesized polymer exhibited good adherent behavior on electrode surface. It exhibited three oxidation peaks at approximately 0.283 V, 0.541 V and 0.989 V and two reduction peaks at 0.1421 and 0.3854 V. Electrical conductivity of PFO doped PANI was studied by impedance spectroscopic method.

Novel polyfuran/functionalized multiwalled carbon nanotubes composites with improved conductivity: Chemical synthesis, characterization, and antioxidant activity

AbstractNovel composites containing very small quantities of functionalized multiwalled carbon nanotubes (MWCNTs‐COOH; 0.025, 0.050, and 0.075 g), and furan were synthesized via in situ chemical oxidative polymerization. The polymerization was carried out in nitromethane at room temperature using anhydrous iron (III) chloride (FeCl3) as an oxidant. The nanocomposites were characterized by Fourier transform infrared, ultraviolet–visible, X‐ray diffraction, differential scanning calorimetry, and field emission scanning electron microscopy. All synthesized composites were crystalline and showed good solubility in dimethyl sulfoxide and N‐methyl 2‐pyrrolidone. The conductivity of composites was measured with a four‐probe method, and it was found that the electrical conductivity increased by increasing the amount of MWCNTs‐COOH. The maximum electrical conductivity value (6.68 × 10−4 S cm−1) was obtained for polyfuran/MWCNTs‐COOH (1:0.075, v/w). The resulting composites were analyzed for their antioxidant activity using 2,2‐diphenyl‐1‐picrylhydrazyl assay. The results showed that the antioxidant activity of the composites increased by increasing the amount of MWCNTs‐COOH in nanocomposite. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers

Synthesis, Characterization, and Bioactivity of Schiff Bases and TheirCd2+,Zn2+,Cu2+, andNi2+Complexes Derived from Chloroacetophenone Isomers with S-Benzyldithiocarbazate and the X-Ray Crystal Structure of S-Benzyl-β-N-(4-chlorophenyl)methylenedithiocarbazate

Two bidentate Schiff base ligands having nitrogen sulphur donor sequence were derived from the condensation of S-benzyldithiocarbazate (SBDTC) with 2-chloroacetophenone and 4-chloroacetophenone to give S-benzyl-β-N-(2-chlorophenyl)methylenedithiocarbazate (NS2) and S-benzyl-β-N-(4-chlorophenyl)methylenedithiocarbazate (NS4) isomers. Each of the ligands was then chelated with Cd2+, Zn2+, Cu2+, and Ni2+. The compounds were characterized via IR spectroscopy and melting point while the structure of NS4 was revealed via X-ray crystallography. Finally, the compounds were screened for antimicrobial activity to investigate the effect that is brought by the introduction of the chlorine atom to the benzene ring. X-ray crystallographic analysis showed that the structure of NS4 is planar with a phenyl ring that is nearly perpendicular to the rest of the molecules. The qualitative antimicrobial assay results showed that NS4 and its complexes lacked antifungal activity while Gram-positive bacteria were generally inhibited more strongly than Gram-negative bacteria. Furthermore, NS4 metal complexes were inhibited more strongly than the ligand while the opposite was seen with NS2 ligand and its complexes due to the partial solubility in dimethyl sulfoxide (DMSO). It was concluded that generally NS2 derivatives have higher bioactivity than that of NS4 derivatives and that the Cd complexes of both ligands have pronounced activity specifically on K. rhizophila.

Sodium hydroxide permethylation of heparin disaccharides

Permethylation is a valuable and widely used tool for the mass spectrometry of carbohydrates, improving sensitivity and fragmentation and increasing the amount of information that can be obtained from tandem mass spectrometric experiments. Permethylation of most glycans is easily performed with sodium hydroxide and iodomethane in dimethyl sulfoxide (DMSO). However, permethylation has not been widely used in the mass spectrometry of glycosaminoglycan (GAG) oligosaccharides, partly because it has required the use of the difficult Hakomori method employing the methylsulfinylmethanide ('dimsyl') base, which has to be made in a tedious process. Additionally, the Hakomori method is not as effective as the sodium hydroxide method in making fully methylated derivatives. A further problem in the permethylation of highly sulfated oligosaccharides is their limited solubility in DMSO. This paper describes the use of the triethylammonium counterion to overcome this problem, as well as the application of the sodium hydroxide method to make permethylated heparin disaccharides and their workup to yield fully methylated disaccharides for electrospray ionization mass spectrometry. The ease, speed, and effectiveness of the described methodology should open up permethylation of GAG oligosaccharides to a wider circle of mass spectrometrists and enable them to develop further derivatization schemes in the effort to rapidly elucidate the structure of these important molecules. Permethylation may also provide new ways of separating GAG oligosaccharides in LC/MS, their increased hydrophobicity making them amenable for reversed-phase chromatography without the need for ion pairing reagents.

Viscoelastic properties of highly concentrated maize starch solutions in DMSO

AbstractRheological measurements of highly concentrated dimethylsulfoxide (DMSO) starch solutions were performed. For all experiments commercial maize starch with different AM content was used. The research covered a wide range of polymer concentrations depending on linear fraction contribution and allowed to obtain a starch content up to 40% w/w. The analysis covered the time – concentration superposition method and fitting the continuous Maxwell model to the experimental data using Tikhonov regularization method. The results allowed statements about the viscoelastic behavior of non‐aqueous starch solutions, depending on their molecular structure. If the linear AM is the predominant component of the starch, the system behaves more elastic compared to those composed of branched AP. The effect of variation in molecular constitution is stronger than the effect of concentration of the dispersion. Additionally, the molecular masses of both fractions seems not to be the crucial factor for rheological properties as well as biopolymer solubility in DMSO. Relaxation spectra obtained from Maxwell model show the drift of the main peak to shorter relaxation times when the concentration of biopolymer is rising. The phenomenon testifies about the influence of starch concentration on elastic response of the system.

Delta inulin: a novel, immunologically active, stable packing structure comprising -D-[2 -> 1] poly(fructo-furanosyl) -D-glucose polymers

We report a novel isoform of β-D-[2 → 1] poly(fructo-furanosyl) α-D-glucose termed delta inulin (DI), comparing it with previously described alpha (AI), beta (BI) and gamma (GI) isoforms. In vitro, DI is the most immunologically active weight/weight in human complement activation and in binding to monocytes and regulating their chemokine production and cell surface protein expression. In vivo, this translates into potent immune adjuvant activity, enhancing humoral and cellular responses against co-administered antigens. As a biocompatible polysaccharide particle, DI is safe and well tolerated by subcutaneous or intramuscular injection. Physico-chemically, DI forms as an insoluble precipitate from an aqueous solution of suitable AI, BI or GI held at 37-48°C, whereas the precipitate from the same solution at lower temperatures has the properties of AI or GI. DI can also be produced by heat conversion of GI suspensions at 56°C, whereas GI is converted from AI at 45°C. DI is distinguished from GI by its higher temperature of solution in dilute aqueous suspension and by its lower solubility in dimethyl sulfoxide, both consistent with greater hydrogen bonding in DI's polymer packing structure. DI suspensions can be dissolved by heat, re-precipitated by cooling as AI and finally re-converted back to DI by repeated heat treatment. Thus, DI, like the previously described inulin isoforms, reflects the formation of a distinct polymer aggregate packing structure via reversible noncovalent bonding. DI forms the basis for a potent new human vaccine adjuvant and further swells the growing family of carbohydrate structures with immunological activity.

Removing Highly Cohesive Silicone Gel after Breast Implant Rupture: An In Vitro Study

Sir: After breast implant rupture, the silicone gel must be removed thoroughly from surrounding tissues to prevent inflammatory reaction, granuloma formation, and possible local infection. The fourth generation of implants commonly used today contains highly cohesive silicone gel. We know little about its gel-dissolving qualities. This study sought to determine which of the commonly used operating room irrigation solutions is best for dissolving the highly cohesive silicone gel. Special attention was given to dimethyl sulfoxide solution because of its chemical1 and clinical antiinflammatory2,3 and anticollagenous4 properties. Gravimetry was used to test silicone gel solubility in dimethyl sulfoxide and other agents commonly used in the operating room, as follows: Normal saline (0.9% sodium chloride). Iodine solution 10%. Polydine scrub (7.5% povidone-iodine with sodium laureth sulfate, potassium iodide, and trisodium phosphate). Unisept (0.05% chlorhexidine gluconate in aqueous solution containing sodium hydroxide, nonoxynol 10, and carnosine red). Hydrogen peroxide 3%. Septal scrub (chlorhexidine gluconate 4%). Aliquots of the gel from a new silicone gel implant (Mentor Corp., Santa Barbara, Calif.) were spread onto glass microscope slides in incremental weights of 0.02, 0.04, 0.06, and 0.08 g. Each slide was soaked in 40 ml of solvent for 2 minutes, rinsed with 80 cc of deionized water for 30 seconds, and placed in a vacuum desiccator for 24 hours. The percentage reduction in silicone weight was calculated for each solvent. Experiments were repeated six times. Results were confirmed by gas chromatography. None of the solutions examined, including dimethyl sulfoxide, dissolved the silicone gel. By gravimetry, the postsolvent silicone gel weights were equal to or, in some cases, even higher than the presolvent weights. Chromatography failed to yield a peak that might have been explained by silicone gel solubility. This study sought to determine the ability of dimethyl sulfoxide and other irrigation solutions to serve as a solvent for breast implant silicone gel. We assumed that the unique chemical structure and high solvent qualities of dimethyl sulfoxide would make it a good candidate agent for cleaning the breast pocket after implant rupture. Moreover, dimethyl sulfoxide, because of its proven clinical properties, such as maintenance of lysosomal integrity, inhibition of fibroblast proliferation, and antibacterial action, could have added value by decreasing capsular contracture and infection rates. Using both gravimetry and gas chromatography, we found that dimethyl sulfoxide, like all the other solutions studied, was ineffective in dissolving the highly cohesive silicone gel. Our findings disagree with those of Bitar et al.5 for saline and iodine solutions. The discrepancy in the results might be attributed to changes made in the cohesiveness of the gel in the interim between the two studies. The new, highly cohesive, silicone gel is difficult to dissolve in cases of implant rupture, and cleansing of the breast pocket is achieved by debulking only. Further studies are required to determine whether dimethyl sulfoxide, because of its clinical properties, has an advantage over saline in this setting by reducing the capsular contracture rate. DISCLOSURE No financial support or benefits have been received by any of the authors from any commercial source that is related directly or indirectly to the scientific work reported on in this article. Sagit Meshulam-Derazon, M.D. Department of Plastic Surgery Rabin Medical Center Beilinson Campus Petah Tiqwa, Israel and Sackler Faculty of Medicine Tel Aviv University Tel Aviv, Israel Igal Bar-Ilan, Ph.D. MIGAL-Research Institute Kiryat Shmona, Israel Ron Azaria, M.D. Dean Ad-El, M.D. Department of Plastic Surgery Rabin Medical Center Beilinson Campus Petah Tiqwa, Israel and Sackler Faculty of Medicine Tel Aviv University Tel Aviv, Israel

Electrochemical synthesis and spectroelectrochemical behavior of poly(diphenylamine-co-4,4′-diaminodiphenyl sulfone)

The electroactive copolymer of diphenylamine (DPA) and 4,4′-diaminodiphenyl sulfone (DADPS) was synthesized electrochemically in 4 M H 2SO 4 and ethanol medium. Both electrochemical synthesis and characterization of the copolymer deposited on a glassy carbon electrode (GCE) were carried out using cyclic voltammetry. The voltammograms exhibited different patterns of behavior with different feed concentrations of DPA. Equimolar concentrations of DPA and DADPS demonstrated very efficient growth of the copolymer film on the surface of the GCE. The copolymer exhibited high solubility in dimethyl sulfoxide (DMSO). The scan rate exerted little-effect on this GCE copolymer film, revealing the film's excellent electroactive adherent properties. The effect of pH on the copolymer film showed that the polymer was electrochemically active up to pH 7.0. Spectroelectrochemical analysis of the copolymer film, carried out on an indium tin oxide (ITO) plate, showed multicolor electrochromic behavior when the applied potential was changed. The copolymer was characterized by FTIR and 1H NMR spectral data. The surface morphology was studied using SEM analysis, the grain size of the copolymer was measured using XRD studies and was found to be 56 nm. The electrical conductivity of the copolymer was 2.65 × 10 −2 S cm −1, as determined using a four-probe conductivity meter.

Synthesis and properties of novel side-chain-type sulfonated polyimides

A series of side-chain-type sulfonated polyimides (SPIs) were synthesized from 4,4′-ketone dinaphthalene-1,1′,8,8′-tetracarboxylic dianhydride (KDNTDA), 2,2′-(4-sulfophenoxy) benzidine, and nonsulfonated diamines. The SPIs showed anisotropic membrane swelling in water with 2–4 times larger swelling in thickness direction than that in plane one, being much different from SPIs derived from 1,4,5,8-naphthalenetetracarboxylic dianhydride. They exhibited good solubility in dimethyl sulfoxide and 1-methyl-2-pyrrolidone even in proton form, which is favorable for processing in fuel cell applications. KDNTDA-based SPIs displayed good mechanical properties with reduced viscosities ranged from 1.1 to 2.4 dl g−1 at 35 °C in triethylamine salt form. They also showed reasonably high proton conductivity and thermal stability.

Preparation and characterization of soluble methyl- β-cyclodextrin functionalized single-walled carbon nanotubes

Methyl- β-cyclodextrin and octadecylamine-modified single-walled carbon nanotube composites were prepared using standard techniques. Oxidized single-walled carbon nanotube was acyl halogenated with thionyl chloride and dimethylformamide, then reacted with methyl- β-cyclodextrin and octadecylamine simultaneously to obtain soluble products. The formation of surface functional groups and changes of nanotubes structures of functionalized single-walled carbon nanotubes were monitored by Fourier transform infrared spectroscopy and transmission electron microscopy, respectively. The functionalized single-walled carbon nanotubes have substantial solubility in dimethyl sulfoxide and dimethylformamide.

Synthesis of novel sulfonated polybenzimidazole and preparation of cross-linked membranes for fuel cell application

A novel sulfonated polybenzimidazole, sulfonated poly[2,2′-(p-oxydiphenylene)-5,5′-bibenzimidazole] (SOPBI), was successfully prepared by post-sulfonation reaction of the parent polymer, poly[2,2′-(p-oxydiphenylene)-5,5′-bibenzimidazole] (OPBI), using concentrated and fuming sulfuric acid as the sulfonating reagent at 80°C, and the degree of sulfonation (DS) could be regulated by controlling the reaction conditions. No significant polymer degradation was observed in the post-sulfonation processes. Direct polymerization of 4,4′-dicarboxydiphenyl ether-2,2′-disulfonic acid disodium salt (DCDPEDS) and 3,3′-diaminobenzidine (DABz), however, resulted in insoluble gels either in polyphosphoric acid (PPA) or in phosphorus pentoxide/methanesulfonic acid (PPMA) in a ratio of 1:10 by weight reaction medium. The SOPBIs prepared by the post-sulfonation method showed good solubility in dimethyl sulfoxide (DMSO), high thermal stability, good film forming ability and excellent mechanical properties. Cross-linked SOPBI membranes were successfully prepared by thermal treatment of phosphoric acid-doped SOPBI membranes at 180°C in vacuo for 20h and the resulting cross-linked membranes showed much improved water stability and radical oxidative stability in comparison with the corresponding uncross-linked ones, while the proton conductivity did not change largely. Highly proton conductive (150mScm−1, 120°C in water) and water stable SOPBI membrane was developed.