Electrical functionalities of poly(n‐hexyl isocyanate) in solid phase

We report electrical functionalities of a rigid rod‐like helical polymer, poly(n‐hexyl isocyanate) (PHIC), in the solid state. Our experimental results of a displacement (D)–field (E) hysteresis and a measurement of pyroelectric signal proved that the PHIC system was electrically active. From the D–E hysteresis loop, coercive field and remanent polarization were determined to be 6.8 MV/m and 3.0 mC/m², respectively, at 80 °C. The pyroelectric coefficient was 9.5 mC/m² K for the sample for which the poling treatment was conducted at 80 °C with the field 20 MV/m. The dipole ordering of the C?O dipoles attached to the main chain was responsible for these electrical activities. Relatively small amounts of the remanent polarization and the pyroelectric coefficient possibly resulted from the short‐range dipole ordering in the noncrystalline phase. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3093–3099, 2005     

Weyl transformation in Fermi systems

In the path integral representation, the Hamiltonian in a quantum system is associated with the Hamiltonian in a classical system through the Weyl transformation. From this, it is possible to describe the time evolution in a quantum system by the Hamiltonian in a classical system. In a Bose system, the Weyl transformation is defined by the eigenstates of the canonical operators, since the Hamiltonian is given by a function of the canonical operators. On the other hand, in a Fermi system, the Hamiltonian is usually described by a function of the creation and annihilation operators, and hence the Weyl transformation is defined by the coherent states which are the eigenstate of an annihilation operator. Here, we formulate the Weyl transformation in Fermi systems in terms of the eigenstates of the canonical operators so as to clarify the correspondence between both systems. Using this, we can derive the path integral representation in Fermi systems.     

High repetition rate femtosecond WDM pulse generation using direct space-to-time pulse shapers and arrayed waveguide gratings

For the application of high repetition rate wavelength division multiplexed (WDM) pulse train generation from a femtosecond modelocked fiber laser, the direct space-to-time pulse shaper and a properly designed arrayed waveguide grating (AWG) are equivalent. The analogy between the bulk optics and integrated configuration is explored for this application. The critical design parameters of the AWG are the free spectral range and the pathlength difference between adjacent guides in the array.     

A novel synthetic procedure of vinylacetamide and its free radical polymerization

The pyrolysis of N-(α-methoxyethyl) acetamide, which was obtained by one-step reaction of acetamide, acetaldehyde, and methanol, gave N-vinylacetamide (NVA) in a good yield. The polymerizability and copolymerizability of NVA were studied. Free radical polymerization was carried out in the presence of radical initiator or by γ-ray irradiation. The monomer reactivity ratios of NVA were estimated in the copolymerization with acrylamide, vinyl acetate, and methyl methacrylate. The solvents were found to influence the monomer reactivity ratio. NVA showed a typical copolymerizability as nonconjugated vinyl monomer, and Q and e values were obtained in DMF as 0.16 and ?1.57, respectively.     

Excited states of poly(vinyl cinnamate) studied by low-energy electron loss spectroscopy and inmdo/s computation

The low-energy electron loss spectrum of poly (vinyl cimiamate) film was measured as a function of impact energy. Excited states of the polymer were also investigated by an INDO/S MO calculation using cinnamic acid as a model. The calculated results agree well with the experimental results both for triplet and singlet excitations, indicating that the observed excitations (2.8, 4.5, 5.8 and 7 eV) are localized in the pendant group of the polymer.     

Convection-aided collection of metal ions using chelating porous flat-sheet membranes

Chelating porous membranes were prepared by radiation-induced graft polymerization of an epoxy-group-containing monomer onto a polyethylene flat sheet and subsequent conversion of the epoxy group to an iminodiacetate group as a chelate-forming group. The chelating group density on the resultant porous flat-sheet membrane of 1.0 mol/kg was comparable to that of commercially available chelating beads. The pure water permeability of the membrane was 40% that of the trunk porous membrane, which was used for microfiltration. During the permeation of a copper chloride solution through the membrane, diffusional mass-transfer resistance of copper ion was negligible, since the ion was transported by convective flow through the pore. The tensile strength and elongation at break of the membranes were measured as a function of dose of electron-beam irradiation, the degree of grafting, and the chelating group density to determine an applicable range for practical use.     

The Catalysis of Vapor-Phase Beckmann Rearrangement for the Production of ε-Caprolactam

Recently, Sumitomo Chemical Co., Ltd. developed the vapor-phase Beckmann rearrangement process for the production of -caprolactam. In the process, cyclohexanone oxime is rearranged into -caprolactam using a zeolite as a catalyst instead of sulfuric acid. EniChem in Italy developed the ammoximation process that involves the direct production of cyclohexanone oxime without producing any ammonium sulfate. Sumitomo Chemical Co., Ltd. has commercialized the combined process of vapor-phase Beckmann rearrangement and ammoximation in 2003.In this paper, the authors focus on some aspects of the vapor-phase Beckmann rearrangement catalysis. A solid catalyst that is mainly composed of a high-silica MFI zeolite (Silicalite-1) has been developed for the vapor-phase Beckmann rearrangement. This catalyst does not possess acidity that can be detected by ammonia TPD. Methanol fed into the reactor with cyclohexanone oxime improves the yield of caprolactam. Methanol reacts with terminal silanols on the zeolite surface and converts them to methoxyl groups. The modification of the catalyst by methanol has an important role for the Beckmann rearrangement reaction.Nest silanols located just inside the pore mouth of the MFI zeolite are supposed to be the active sites of the catalyst. We propose that the coordination between the NOH group of cyclohexanone oxime molecule and the nest silanols through hydrogen bonding is responsible for the reaction. The reaction mechanism of Beckmann rearrangement under vapor-phase conditions is the same as in the liquid phase, namely, the alkyl group in anti-position against the hydroxyl group of the oxime migrates to the nitrogen atom's position.