Sulfonic Acid Salt Research Articles

A Novel Selective Freelayer Wet Etching Method for Magnetic Tunnel Junction-Based MRAM

This paper describes the development of a novel wet etch process for selective patterning of ferromagnetic freelayers, principally Permalloy, in MRAM magnetic tunnel junction (MTJ) stacks. The method uses a nonadsorbing acid, trifluoromethane sulfonic (TFMSA), as the etchant acid. Freelayer etch selectivity to the alumina tunneling barrier is achieved through the use of long-chain alkane sulfonic acid salts, e.g. sodium 1-tetradecanesulfonate. These inhibitors can increase the alumina barrier etch resistance in the TFMSA solution by up to two orders of magnitude. The importance of the reactive ion etching process used for MTJ cap layer removal prior to the wet etching step is discussed. Open circuit potential (OCP) was shown to be a powerful method for following the progress of freelayer wet etching and for evaluating alumina barrier etch inhibitors.

Design of New Oxazaphosphorine Anticancer Drugs

The oxazaphosphorines including cyclophosphamide (CPA, Cytoxan, or Neosar), ifosfamide (IFO, Ifex) and trofosfamide (Ixoten) represent an important group of therapeutic agents due to their substantial antitumor and immunomodulating activity. However, several intrinsic limitations have been uncounted during the clinical use of these oxazaphosphorines, including substantial pharmacokinetic variability, resistance and severe host toxicity. To circumvent these problems, new oxazaphosphorines derivatives have been designed and evaluated with an attempt to improve the selectivity and response with reduced host toxicity. These include mafosfamide (NSC 345842), glufosfamide (D19575, beta-D-glucosylisophosphoramide mustard), S-(-)-bromofosfamide (CBM-11), NSC 612567 (aldophosphamide perhydrothiazine) and NSC 613060 (aldophosphamide thiazolidine). Mafosfamide is an oxazaphosphorine analog that is a chemically stable 4-thioethane sulfonic acid salt of 4-hydroxy-CPA. Glufosfamide is IFO derivative in which the isophosphoramide mustard, the alkylating metabolite of IFO, is glycosidically linked to a beta-D-glucose molecule. Phase II studies of glufosfamide in the treatment of pancreatic cancer, non-small cell lung cancer (NCSLC), and recurrent glioblastoma multiform (GBM) have recently completed and Phase III trials are ongoing, while Phase I studies of intrathecal mafosfamide have recently completed for the treatment of meningeal malignancy secondary to leukemia, lymphoma, or solid tumors. S-(-)-bromofosfamide is a bromine-substituted IFO analog being evaluated in a few Phase I clinical trials. The synthesis and development of novel oxazaphosphorine analogs with favourable pharmacokinetic and pharmacodynamic properties still constitutes a great challenge for medicinal chemists and cancer pharmacologists.

Morphology, structure, and conductivity of polypyrrole prepared in the presence of mixed surfactants in aqueous solutions

AbstractPolypyrrole (PPy) was prepared from different mixed‐surfactant solutions with ammonium persulfate as an oxidant. Three types of combinations were selected, including cationic/anionic, cationic/nonionic, and anionic/nonionic mixed‐surfactant solutions. The surfactants used in the experiments included cetyltrimethylammonium bromide (cationic surfactant), sodium dodecyl sulfate (anionic surfactant), sodium dodecyl sulfonic acid salt (anionic surfactant), poly(vinyl pyrrolidone) (nonionic surfactant), and poly(ethylene glycol) (nonionic surfactant). The morphology, structure, and conductivity of the resulting PPy were investigated in detail with scanning electron microscopy, Fourier transform infrared spectra, and the typical four‐probe method, respectively. The results showed that the interaction between the different surfactants and the interaction between the surfactants and the polymer influenced the morphology, structure, and conductivity of the resulting polymer to different degrees. The cationic surfactant favored the formation of nanofibers, the addition of anionic surfactants produced agglomeration but enhanced the doping level and conductivity, and the presence of a nonionic surfactant weakened the interaction between the other surfactant and the polymer in the system. In comparison with the results for monosurfactant solutions, the polymerization of pyrrole in mixed‐surfactant solutions could modulate the morphologies of PPy, which ranged from nanofibers of different lengths to nanoparticles showing various states of aggregation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1987–1996, 2007

Complexes of barium ions with quercetin-5′-sulfonic acid and sodium salt of morin-5′-sulfonic acid

Complex formation of Ba2+ ions with quercetin-5′-sulfonic acid and sodium salt of morin-5′-sulfonic acid was studied by potentiomety. Solid complexes were obtained, and their composition and physicochemical properties were studied.

Salt Tolerance of an Aqueous Solution of a Novel Amphiphilic Polysaccharide Derivative

An aqueous solution of an amphiphilic polysaccharide derivative, hydrophobically (stearyl alkyl group) and hydrophilically (sulfonic-acid salt group) modified hydroxyethylcellulose (HHM-HEC), showed increased viscosity, elasticity, and thixotropic properties in response to the addition of monovalent and divalent salts. Furthermore, the HHM-HEC solution had a transparent appearance at a NaCl concentration of 7 wt %. Since it showed superior salt tolerance to HEC, we focused attention on the two substituents of HHM-HEC and prepared HEC derivatives, namely, hydrophobically modified hydroxyethylcellulose (R-HEC), hydrophilically modified hydroxyethylcellulose (S-HEC), and nonmodified hydroxyethylcellulose (HEC). In addition, we used oscillatory, thixotropic, and fluorometric methods to compare the rheological properties of HHM-HEC with those of other derivatives in the presence of NaCl and ZnCl2, and attempted to elucidate the respective roles of the two substituents of HHM-HEC solution in the salt-tolerance mechanism. As the NaCl concentration in the HHM-HEC solution increased, the values of the elastic modulus G' and the viscous modulus G'' increased, and, moreover, the relative intensities of the first (I1 = 372 nm) and the third (I3 = 383 nm) vibronic bands of the pyrene monomer emission spectrum (the I1/I3 ratio) decreased. These results suggested that the added salt strengthened the three-dimensional network structure of the HHM-HEC polymer by the formation of cross-linkages through the association of hydrophobic substituents. This hydrophobic substituent was therefore essential in allowing HHM-HEC to exhibit a high viscosity in a salt solution. Although the R-HEC solution showed a higher viscosity than did the HHM-HEC solution in the absence of added salts, it became cloudy and lost its viscosity at high NaCl concentrations, apparently because of the shrinkage of its network structure. This signified that the hydrophilic substituent was essential for the sufficient solubility of HHM-HEC to show its rheological properties in a salt-rich solution. We propose to explain how the viscosity of HHM-HEC increases in the presence of salts as follows: Added salts weaken the electrostatic repulsion between the hydrophilic substituents, thereby enhancing the interactions of hydrophobic substituents and consequently increasing the rigidity of the HHM-HEC solution.

Preparation and Gas Permeation Properties of Composite Carbon Molecular Sieve Membranes Derived from Polyimides with Thermally Decomposable Sulfonic Acid Salt and/or Hexafluoroisopropylidene Group

Carbon molecular sieve (CMS) membranes were prepared from polyimides with sulfonic acid triethylammonium salt (SO3NH(C2H5)3) and/or hexafluoroisopropylidene (–C(CF3)2–) groups by pyrolyzing precursor composite membranes at the temperatures ranging from 773 to 973 K in an N2 flow for 1 h. The precursor membranes were prepared by coating the polyimides on ceramic porous support tubes. The sulfonic acid salt and the –C(CF3)2– group decomposed in the ranges of 573 to 673 K and 723 to 973 K, respectively. The composite CMS membranes prepared here had a defect-free top layer of 1.5 to 5 μm thick. The CMS membrane derived from the polyimide with both the thermally decomposable groups displayed the highest gas permeances. The decomposition of sulfonic acid groups followed by the decomposition of the –C(CF3)2– group just before the substantial decomposition of the polyimide backbone seemed to significantly enhance the micropore structure of the resultant pyrolytic layer. Compared to the CMS composite or hollow-fiber membranes reported in the literature, the membranes prepared in this study displayed higher O2 and CO2 gas permeances with reasonably high ideal separation factors for O2/N2 and CO2/N2 separations.

Decomposition of energetic chemicals contaminated with iron or stainless steel

Contamination of chemicals or reaction mixtures with iron or stainless steel is likely to take place during chemical processing. If energetic and thermally unstable chemicals are involved in a manufacturing process, contamination with iron or stainless steel can impact the decomposition characteristics of these chemicals and, subsequently, the safety of the processes, and should be investigated. The goal of this project was to undertake a systematic approach to study the impact of iron or stainless steel contamination on the decomposition characteristics of different chemical classes. Differential scanning calorimetry (DSC) was used to study the decomposition reaction by testing each chemical pure, and in mixtures with iron and stainless steel. The following classes of energetic chemicals were investigated: nitrobenzenes, tetrazoles, hydrazines, hydroxylamines and oximes, sulfonic acid derivatives and monomers. The following non-energetic groups were investigated for contributing effects: halogens, hydroxyls, amines, amides, nitriles, sulfonic acid esters, carbonyl halides and salts of hydrochloric acid. Based on the results obtained, conclusions were drawn regarding the sensitivity of the decomposition reaction to contamination with iron and stainless steel for the chemical classes listed above. It was demonstrated that the most sensitive classes are hydrazines and hydroxylamines/oximes. Contamination of these chemicals with iron or stainless steel not only destabilizes them, leading to decomposition at significantly lower temperatures, but also sometimes causes increased severity of the decomposition. The sensitivity of nitrobenzenes to contamination with iron or stainless steel depended upon the presence of other contributing groups: the presence of such groups as acid chlorides or chlorine/fluorine significantly increased the effect of contamination on decomposition characteristics of nitrobenzenes. The decomposition of sulfonic acid derivatives and tetrazoles was not impacted by presence of iron or stainless steel.

Surfactants and interfacial phenomena

Surfactants and interfacial phenomena

Solution Properties of a Novel Polysaccharide Derivative

Abstract A novel self-assembly polysaccharide derivative; hydrophobically (stearyl alkyl group) and hydrophilically (sulfonic acid salt group) modified hydroxyethylcellulose (HHM-HEC), has the unique rheological properties in aqueous solutions.

Layered double hydroxide-like materials: nanocomposites for use in concrete

Nitrobenzoic acid (NBA), naphthalene-2, 6-disulfonic acid (26NS), and naphthalene-2 sulfonic acid (2NS) salts were intercalated into a layered double hydroxide-like host material (LDH). The intercalation process was achieved by anion exchange of nitrates in the host material, Ca 2Al(OH) 6NO 3, nH 2O (CaAl LDH), which was prepared by a coprecipitation technique. The resulting organo derivatives CaAlNBA LDH, CaAl26NS LDH, and CaAl2NS LDH produced a tilted orientation of NBA and 26NS anions in the interlayer space, while 2NS anions induced a perpendicular bilayer arrangement. Materials characterization was carried out using X-ray diffraction (XRD), IR-spectroscopy, thermal analysis, and scanning electron microscopy (SEM). These preliminary results open up a new direction towards the synthesis of nanocomposites using polymeric entities and layered materials for future applications in cement and concrete science, e.g., control of the effect of admixtures on the kinetics of cement hydration by programming their temporal release.

Direct Synthesis of Sulfonamides and Activated Sulfonate Esters from Sulfonic Acids.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Preparation and properties of waterborne polyurethane/polyaniline codoped with dodecyl benzene sulfonic acid and hydrochloric acid blends

AbstractA conductive poly(aniline codoped with dodecyl benzene sulfonic acid and hydrochloric acid) [PANI‐D/H, yield: 32.2%, intrinsic viscosity ([η]): 1.39 dL/g, electrical conductivity: 7.3 S/cm] was synthesized by chemical oxidative polymerization from aniline‐dodecylbenzene sulfonic acid salt (A‐DS)/aniline‐hydrochloric acid salt (A‐HS) (6/4M ratio) in an aqueous system. Waterborne polyurethane (WBPU) dispersion obtained from isophorone diisocyanate/poly(tetramethylene oxide)glycol/dimethylol propionic acid/ethylene diamine/triethylene amine/water was used as a matrix polymer. The blend films of WBPU/PANI‐D/H with various weight ratios (99.9/0.1–25/75) were prepared by solution blending/casting. Effect of PANI‐D/H content on the mechanical property, dynamic mechanical property, hardness, electrical conductivity, and antistaticity of WBPU/PANI‐D/H blend films was investigated. The dynamic storage modulus and initial tensile modulus increased with increasing PANI‐D/H content up to 1 wt %, and then it was significantly decreased about the content. With increasing PANI‐D/H content, the glass transition temperature of soft segment (Tgs) and hard segment (Tgh) of WBPU/PANI‐D/H blend films were shifted a bit to lower the temperature. The tensile strength and hardness of WBPU/PANI‐D/H blend films increased a little with increasing PANI‐D/H content up to 0.5 wt %, and then it was dramatically decreased over the content. The elongation at break of WBPU/PANI‐D/H decreased with an increase in PANI‐D/H content. From these results, it was concluded that 0.5–1 wt % of PANI‐D/H was the critical concentration to reinforce those various properties of WBPU/PANI‐D/H blend films prepared in this study. The electrical conductivity of WBPU/ultrasonic treated PANI‐D/H (particle size: 0.7 μm) blend films prepared here increased from 4.0 × 10−7 to 0.33 S/cm with increasing PANI‐D/H content from 0.1 to 75 wt %. The antistatic half‐life time (τ1/2) of pure WBPU film was about 110 s. However, those of WBPU/ultrasonic treated PANI‐D/H blend films (τ1/2: 8.2–0.1 s, and almost 0 s) were found to decrease exponentially with increasing PANI‐D/H content (0.1–9 wt %, and above 9 wt %). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 700–710, 2004

Direct Synthesis of Sulfonamides and Activated Sulfonate Esters from Sulfonic Acids

A general new method for the preparation of sulfonamides and activated sulfonate esters by the direct coupling of sulfonic acid salts with amines and alcohols using the reagent triphenylphosphine ditriflate is described. A new reusable polymer-supported reagent for these transformations under heterogeneous conditions is also described. These methods provide a fundamentally new approach to making small molecules containing the sulfonamide functional group.

Corrosion Protection of Mild Steel Using Sulfonic and Phosphonic Acid-Doped Polyanilines

Abstract Growing environmental concerns regarding the use of heavy metals in coating formulations have led to a new coating strategy using inherently conducting polymers (ICP), such as polyaniline (PANI), as a key component. The principal potential advantage offered by the ICP coating technology is toleration of pinholes and minor scratches. This paper introduces the use of new PANI formulations that are doped with phosphonic acids. Salt fog exposure tests point to phosphonic acid salts of PANI being more effective for corrosion protection than traditionally used sulfonic acid salts. Scanning reference electrode technology (SRET) data support the salt fog results in that the sulfonic acid dopants exhibited an increasing galvanic activity with time while the phosphonic acid dopants showed a decrease in activity with time, indicating passivation. A qualitative model is proposed which entails passivation of the metal surface through anodization of the metal by PANI and formation of an insoluble iron-dopant s...

Copolymerization of Acrylamido Sulfonic Acids with Acrylamide and Acrylonitrile in Concentrated Neutral Aqueous Solutions

Copolymerization of alkali metal salts of acrylamido sulfonic acids with acrylamide and acrylonitrile in concentrated aqueous solutions was studied. The influence of the chemical nature, ratio, and physical interactions of monomers on polymerization and on the intrinsic viscosity of the copolymers was examined.

亜鉛精鉱の直接浸出と浸出残さからの元素硫黄の回収に関する研究

Zinc concentrate is usually roasted as pretreatment in zinc hydrometallurgy and the produced SO2 is changed to sulfuric acid. However, recently in Japan the utilization of sulfuric acid has been limited and it is more costly to store. In this study, a zinc concentrate (sphalerite) was leached with ferric sulfate at about 373 K for 3 to 6 hours. Then, zinc was leached about 94% and after a solid-liquid separation, the leach residue containing solid elemental sulfur was obtained. After direct leaching, the leach residue was filtrated and the elemental sulfur rich solids were recovered as float product by sink-float separation followed by flotation. In the flotation, lignine sulfonic acid salt as dispersant and MIBC as frother were effective to float sulfur at pH4. The solid elemental sulfur of approximately 97% was recovered as float product by sink-float separation and flotation. The dried mixed float product by sink-float separation and flotation was heated at 413 K for 2 hours and about 87.7% of solid elemental sulfur produced by direct leaching was recovered as pure sulfur.

A Mechanistic Investigation of Polyaniline Corrosion Protection Using the Scanning Reference Electrode Technique

Growing environmental concerns regarding the use of heavy metals in coating formulations have lead to a new coating strategy employing inherently conducting polymers (ICPs), such as polyaniline (PANI), as a key component. The principal potential advantage offered by the ICP coating technology is toleration of pinholes and minor scratches. This paper describes the application of the scanning reference electrode technique (SRET) to the study of PANI coatings on carbon steel. SRET results demonstrate that conductive PANI “passivates” pinhole defects in coatings on carbon steel. In addition, it is shown that phosphonic acid salts of PANI are more effective for corrosion protection than sulfonic acid salts. A model is proposed which entails passivation of the metal surface through anodization of the metal by PANI and formation of an insoluble iron‐dopant salt at the metal surface. © 1999 The Electrochemical Society. All rights reserved.

Plasticization of poly(styrene‐b‐isobutylene‐b‐styrene) ionomers by acid salts of 2‐ethylhexyl‐p‐dimethylaminobenzoate

AbstractPoly(styrene‐b‐isobutylene‐b‐styrene) block copolymer ionomer (overall molecular weight = 71,200 g/mole; 25.5 wt% polystyrene, 4.7% sulfonation of phenyl units, 100% neutralized with KOH) was compounded with various organic and inorganic acid salts of 2‐ethylhexyl‐p‐dimethylaminobenzoate (ODAB) to explore the efficacy of these compounds as ionic plasticizers. Results were compared to the same polymer plasticized by zinc stearate. Plasticizers were added to the polymer at levels of ≈5 wt%. Films were prepared by solution casting from tetrachloroethylene. Thermogravimetric analysis (TGA) showed all ODAB derivatives to have lower decomposition temperatures than zinc stearate. Dynamic mechanical analysis (DMA) of the films showed varying degrees of ionic plasticization as evidenced by a lowering of the temperature at which the onset of flow occurred. With the exception of the stearic acid salt of ODAB, all ODAB derivatives were more efficient ionic plasticizers than zinc stearate. Among the ODAB derivatives, the degree of ionic plasticization varied, with the methane sulfonic and p‐toluene sulfonic acid salts being most effective, leading to the conclusion that processing temperatures could be tailored to specific applications by choice of plasticizer and level of incorporation.

Nematic ionomers as materials for the build-up of multilayers

This paper describes the synthetic route to semiflexible polyesters exhibiting the phases glassy, nematic, isotropic, as well as their functionalization with ionic groups. As ionic groups the salts of sulfonic acids and phosphonic acids were used. These ionic LC-polymers (mostly ionomers) can be used for a multilayer build-up with amorphous polyelectrolytes. The multilayer build-up can be followed by UV spectroscopy, X-ray reflectivity and surface plasmon spectroscopy. The thickness of the sublayers is in the range of 25 to 55 A, and also depends on the polarity of the solvent and on such details as drying or not during the dipping cycle.

Nematic ionomers as materials for the build-up of multilayers

This paper describes the synthetic route to semiflexible polyesters exhibiting the phases glassy, nematic, isotropic, as well as their functionalization with ionic groups. As ionic groups the salts of sulfonic acids and phosphonic acids were used. These ionic LC-polymers (mostly ionomers) can be used for a multilayer build-up with amorphous polyelectrolytes. The multilayer build-up can be followed by UV spectroscopy, X-ray reflectivity and surface plasmon spectroscopy. The thickness of the sublayers is in the range of 25 to 55 Å, and also depends on the polarity of the solvent and on such details as drying or not during the dipping cycle.