Sorption,diffusion, and partial molar volumes of C4 hydrocarbons in rubbery polymers

Sorption and dilation isotherms and diffusion coefficients for seven hydrocarbons (n-butane, isobutane, 1-butene, cis-2-butene, trans-2-butene, isobutylene, and 1,3-butadiene) in two rubbery polymers, 1,2-polybutadiene (PB) and poly(ethylene-co-vinyl acetate) (EVAc), were measured at 25°C. Dissolution parameters (Henry's law coefficient and Flory-Huggins interaction parameter), partial molar volumes, and diffusion coefficients were determined. PB exhibited greater affinity and lower diffusivity than EVAc to the C₄ gases, although the gases showed nearly the same partial molar volumes in the two polymers. The diffusivity of such elongated molecules as trans-2-butene in both polymers was higher than that of bulky molecules with similar partial molar volume, such as cis-2-butene and isobutylene. Pressure-dependent permeabilities of PB and EVAc films to the hydrocarbons were predicted and discussed based on the dissolution parameters and the diffusivities. © 1995 John Wiley & Sons, Inc.     

Kinetik und Mechanismus der Isomerisations-Polymerisation von 2-Methyl-2-oxazolin durch Benzylchlorid und Benzylbromid als Initiatoren. Einflu? des Halogen-Gegenanions

Ohne Zusammenfassung     

One- and two-phonon vibrational spectra of amorphous As- and Sb-chalcogenide systems

One- and two-phonon infrared and Raman spectra of As- and Sb-chalcogenide systems are reported. Both one- and two-phonon Raman and infrared vibrational spectra exhibit two modes type behaviours characteristics to the vibration modes of AsSe₃, AsS₃, and SbSe₃ pyramids. In the infrared spectra, the larger peak shifts are observed for one phonon frequencies than for two phonon frequencies with the change of the composition x, and its suggests rather big local field effects. The two-phonon coupling parameters of the combination modes are estimated.     

Adsorption of 4-nonylphenol ethoxylates onto insoluble chitosan beads bearing cyclodextrin moieties

In order to develop a treatment method for industrial wastewater, the adsorption of 4-nonylphenol ethoxylates (NPEs), non-ionic surfactants used in the industry, onto chitosan beads having cyclodextrin (CDC beads) was investigated. Three kinds of CDC beads containing different cyclodextrin (CD) moieties were prepared from poly-carboxymethylated α-, β- and γ-CDs. Among α-, β- and γ-CD cavities, β-CD was the most suitable for the adsorption of the phenol derivatives. The amount of adsorption was greater for the NPEs having shorter ethoxylates. Most of the NPE adsorbed on the β-CDC beads were successfully released by the treatment of the CDC beads with various aqueous alcohol solutions. After 20 cycles of the adsorption–desorption were completed, no significant decline in the adsorption amount was observed. Continuous adsorption tests were carried out using the CDC beads filled in a glass column. At the appropriate flow rate, the NPE can be adsorbed with a reasonable saturation amount.     

Theory of soliton-based control of coupled superconducting phase qubits

A simple scheme for controlling the gate operation for qubit–qubit interactions in superconducting phase qubits using a moving fluxon is proposed. The basic unit of our scheme is composed of three capacitively coupled flux-biased phase qubits. One of the qubits acts as a switch connecting the other two (two logical qubits) with an identical energy separation. The fluxon controls the energy separation of the switch qubit via its inductive coupling, leading to the resonance among qubits appropriately adjusting the fluxon velocity. As a result, the resonance is capable of performing a gate operation between two logical qubits. In addition, we show that this provides a simple scheme for generating entangled states of many qubits in solid-state quantum nanocircuits.     

Chiral amide from (1S,2R)-(+)-norephedrine alkaloid in the enantioselective addition of diethylzinc to aryl and heteroaryl aldehydes

Chiral amide synthesized from (1S,2R)-(+)-norephedrine and furoic acid was found to catalyze the enantioselective ethylation of aromatic and heteroaromatic aldehydes to secondary alcohols with 99.8% enantioselectivity at 0 °C without the addition of a promoter such as titanium tetraisopropoxide.     

Polyethylenes bearing a terminal porphyrin group

An α-[Cu(II)-porphyrin]-polyethylene was synthesized for the first time using copper catalyzed 1,3-dipolar azide-alkyne Huisgen cycloaddition yielding highly colored moiety-substituted polyethylene.     

Hybridization of layered niobates with cationic dyes

The hybridization of two different types of organic polycations, 1,1’-dimethyl-4,4’-bipyridinium dications (methyl viologen, MV²⁺) and 5,10,15,20-tetrakis(N-methyl-pyridinium-4-yl)-21H,23H-porphine tetracations (TMPyP⁴⁺), into layered niobates was investigated to construct an efficient dye-modified semiconductor for solar conversion and storage. Two different methods were employed for the direct intercalation of the cationic species, i.e., conventional ion-exchange with K₄Nb₆O₁₇ · 3H₂O as the starting host and a novel acid-base neutralization method with H₄Nb₆O₁₇ as the starting host. These two methods showed totally different behavior and the characteristic features of both will be discussed in relation to the structure of the hybrid formed, the amount of absorption observed for the guest molecules and the intercalation rates. An analysis of the photo-induced electron-transfer reactions will also be discussed to show how control of the intercalation of guest molecules affects the photofunctionality of these unique hybrids.     

Synthesis and properties of naphthalene trimers linked by 1,3,4-oxadiazole spacers

Two types of naphthalene trimers linked by 1,3,4-oxadiazole spacers were synthesized and investigated for their physical and electronic properties. 2,6- and 2,7-isomers on central naphthalene moieties were obtained in the forms of pale yellow solids and colorless crystals, respectively. The melting point of the 2,6-isomer was higher than that of the 2,7-isomer. An X-ray crystallographic analysis revealed a π-stacked column with a short intermolecular distance in the crystals of the 2,6-isomer. The absorption maximum of the 2,6-isomer was red-shifted as compared to that of the 2,7-isomer, indicating a π-conjugation between di-2-naphthyloxadiazole moieties in the 2,6-isomer. The quantum yields of the 2,6- and 2,7-isomers were measured to be 0.97 and 0.74, relative to that of 2,5-di-2-naphthyl-1,3,4-oxadiazole (0.85). Molecular orbital (MO) calculations demonstrated that the 2,6-isomer had a higher electron affinity than the 2,7-isomer. Thus, the crosslinking of building blocks is important for the design of functional materials.