Study on gamma-ray-induced degradation of polymer electrolyte by pH titration and solution analysis

Degradation process of polymer electrolyte was investigated by pH titration and solution analysis. Perfluorosulfonic acid, which is generally used for fuel cells and sensors, was irradiated with gamma-ray. Irradiated samples were immersed in distilled water, and the suspensions were titrated with NaCl solution while pH was monitored. Initial pH without any sodium ion decreased as increase in absorbed dose, indicating acid release from polymer electrolyte. To identify the chemical structure of dissolved species, solution analysis was performed by ion chromatography, total organic carbon (TOC) analyzer, and inductively-coupled plasma atomic emission spectrometry (ICP-AES). It was shown that proton, sulfide ion, fluorine ion and organic carbon were detected in the solution, and the ratio among these ions and atoms changed depending on the irradiation conditions. It shows that the solution analysis can identify the scission site by irradiation sensitively, and gives useful information for investigation of polymer degradation process.     

Highly efficient catalysts‐acetylacetonato complexes of transition metals in the 4th period for ring‐opening polymerization of 1,3‐benzoxazine

Acetylacetonato (acac) complexes of transition metals in the 4th period were examined as catalysts for the ring‐opening polymerization of benzoxazine. This examination revealed that acac complexes of manganese, iron, and cobalt exhibited the highest activity, which was comparable or slightly higher than that exhibited by p‐toluenesulfonic acid. By replacing acac ligand by hexafluoroacetylacetonato (F₆‐acac) ligand, the activity of manganese and iron complexes was remarkably enhanced. These metal F₆‐acac complexes were tolerant to moisture to allow their use under air without special caution. Another advantage was their negligible effect to promote unfavorable weight loss during the polymerization. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 479–484, 2010     

Pulse width modulation (PWM) control of the bending displacement and force generation of ionomer‐based polymer actuators

This paper discusses results of the pulse width modulation (PWM) control of the bending displacement and force generation of ionomer‐based polymer actuators. The idea of PWM control for polymer actuators is based on the frequency dependence on relaxation processes of the bending motion of the actuator. The actuators were fabricated by electroless plating of platinum on a perfluorinated sulfonated polymer (i.e. Nafion). It was noted that the duty cycles of PWM can smoothly control both the displacement and force generated by the actuator. The performance of the actuator was evaluated under 40%RH and 90%RH conditions because of the moisture sensitivity of the actuators. Copyright © 2013 John Wiley & Sons, Ltd.     

Substituent effects of N‐alkyl groups on thermally induced polymerization behavior of 1,3‐benzoxazines

Thermally induced polymerizations of a series of 1,3‐benzoxazines with a variety of substituents on the nitrogen atom were investigated in detail, particularly in the following three aspects of the polymerization: (1) N‐alkyl‐1,3‐benzoxazines are much more reactive than N‐phenyl‐1,3‐benzoxazine. (2) The polymerization rate depended on the bulkiness of the N‐substituent. The bulkier the substituent was, the slower the polymerization was. (3) The polymerizations accompanied weight loss due to the elimination of the corresponding imine (R‐N = CH₂), and its extent became larger when R was more bulky. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2777–2782, 2010     

Adsorption behavior of cationic and anionic species on chitosan resins possessing amino acid moieties.

Chitosan resins modified with amino acids, such as glycine, valine, leucine, and serine, were synthesized for investigating the adsorption behavior of cationic and anionic species, and showed good abilities for the adsorption of trace elements in aquatic media as follows: glycine for lanthanoids at pH 7, leucine for molybdenum at pH 1-5, serine for uranium at pH 2-7, and amino acids for bismuth at pH 1-7. Cationic and anionic species could be adsorbed by a chelating mechanism and an anion-exchange mechanism.     

Synthesis of cross-linked chitosan modified with the glycine moiety for the collection/concentration of bismuth in aquatic samples for ICP-MS determination.

A chelating resin, cross-linked chitosan modified with the glycine moiety (glycine-type chitosan resin), was developed for the collection and concentration of bismuth in aquatic samples for ICP-MS measurements. The adsorption behavior of bismuth and 55 elements on glycine-type chitosan resin was systematically examined by passing a sample solution containing 56 elements through a mini-column packed with the resin (wet volume; 1 ml). After eluting the elements adsorbed on the resin with nitric acid, the eluates were measured by ICP-MS. The glycine-type chitosan resin could adsorb several cations by a chelating mechanism and several oxoanions by an anion-exchange mechanism. Especially, the resin could adsorb almost 100% Bi(III) over a wide pH region from pH 2 to 6. Bismuth could be strongly adsorbed at pH 3, and eluted quantitatively with 10 ml of 3 M nitric acid. A column pretreatment method with the glycine-type chitosan resin was used prior to removal of high concentrations of matrices in a seawater sample and the preconcentration of trace bismuth in river water samples for ICP-MS measurements. The column pretreatment method was also applied to the determination of bismuth in real samples by ICP-MS. The LOD of bismuth was 0.1 pg ml(-1) by 10-fold column preconcentration for ICP-MS measurements. The analytical results for bismuth in sea and river water samples by ICP-MS were 22.9 +/- 0.5 pg ml(-1) (RSD, 2.2%) and 2.08 +/- 0.05 pg ml(-1) (RSD, 2.4%), respectively.     

Analysis of swelling process of protein by positron annihilation lifetime spectroscopy and differential scanning calorimetry

The change in the nanoscopic structure and bound state of water in the protein gel were investigated using positron annihilation lifetime spectroscopy (PALS) and differential scanning calorimetry (DSC). Gelatin was used as a protein. To examine the bound state of water in gelatin gel, the amount of freezing and nonfreezing water in gelatin gels were evaluated by fusion enthalpy of DSC curves. Below water content of 40% (w/w), the whole amount of water was nonfreezing water, whereas above water content of 40% (w/w), the amount of freezing water increased according to increase in water content. To investigate the nanoscopic spatial structure under coexistence of polymer and water, positron annihilation lifetime measurement was performed. The lifetime of o‐Ps or the pore size increased according to increase in water content, particularly below the water content of 40% (w/w). When the water penetrates into the gelatin network, the water molecules form hydrogen bonds with hydrophilic groups inside the helical structure in gelatin gel. The water molecules inside the helical structure expand the structure outward, leading to increase in pore size. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2031–2037, 2007.     

Polyfluorination using IF(5)

The polyfluorination of α-(arylthio)carbonyl compounds was achieved by a successive application of polyfluorination using IF(5), Friedel-Crafts arylation, and desulfurizing fluorination using IF(5). Three to six fluorine atoms were selectively introduced to the carbons located between the aromatic ring and the carbonyl group.     

High pressure synthesis and properties of ternary titanium (III) fluorides in the system KF-TiF3 containing regular pentagonal bipyramids [TiF7]

Titanium trifluoride TiF₃ has the distorted ReO₃ structure composed of corner sharing TiF₆ octahedra linked with Ti-F-Ti bridges. Potassium fluoride KF was inserted into the bridges using high-pressure and high-temperature conditions (5 GPa, 1000-1200 °C). When the molar ratio KF/TiF₃≥1, a few low dimensional compounds were obtained forming non-bridged F ions. At the composition KF/TiF₃=1/2, a new compound KTi₂F₇ was formed, which crystallizes with the space group Cmmm and the lattice parameters of a=6.371(3), b=10.448(6), c=3.958(2) Å, consisting of edge-sharing pentagonal bipyramids [TiF₇] forming ribbons running along the a axis. The ribbons are linked by corners to construct a three-dimensional framework without forming non-bridged F ions. The compound is antiferromagnetic with the Néel temperature T_N=75 K, and the optical band gap was 6.4 eV. A new fluoride K₂TiF₅ (KF/TiF₃=2) with the space group Pbcn and the lattice parameters of a=7.4626(2), b=12.9544(4) and c=20.6906(7) Å was also obtained by the high pressure and high temperature treatment (5 GPa at 1000 °C) of a molar mixture of 2 KF+TiF₃. The compound contains one-dimensional chains of corner-sharing TiF₆ octahedra.