Preparation of thick and hard coating films via sol–gel process with a low temperature treatment

SiO₂-polymer hybrid thick and hard coating films were successfully obtained via sol–gel process with a heat treatment at 200 °C. The films were achieved by control of hydrolysis and poly-condensation reaction of silica species. Key parameters were pH, water content and additional polymer in the coating solution. No-cracking and highly transparent films were formed with polymer content in a range from 28 to 42 mass% [vs. SiO₂]. Their thickness was varied from 2.6 to 3.5 μm with an increase in the polymer content. The haze values of the films after Taber abrasion were very low in a range from 1.3 to 2.7%, and the pencil hardness was over 9H. Moreover, no-damage was observed on the surface after steel wool abrasion with 4 kg loaded. These high mechanical strengths were come up to that of float glass, so that the coating films prepared by this process have a great potential for application to architectural and automotive window glass.     

X-ray Structure of a Pentacarbonyltungsten Complex of 1-Phosphaallene

The structure of a tungstenpentacarbonyl complex of 3, 3-dipheny1-1-(2,4,6-tri-t-butylpheny1)-1-phosphaallene has been determined by X-ray analysis.     

Reactions of a sterically protected 2,3‐dichloro‐1,4‐diphospha‐1,3‐butadiene with some alkyl and hydrido lithium reagents

The reactions of 2,3‐dichloro‐1,4‐diphospha‐1,3‐butadiene, which is sterically protected with the 2,4,6‐tri‐t‐butylphenyl group, with some nucleophiles, including alkyllithium reagents and lithium aluminum hydrides, afforded 1,2‐diphosphinoacetylenes or 3‐phosphino‐1‐phosphaallenes. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:171–176, 2000     

Synthesis of ordered polymer by direct polycondensation. VIII. Ordered polymer from two nonsymmetric monomers

The ordered (-aacdbbdc-) polymer was prepared by the direct polycondensation of a pair of symmetric monomers (XabX), 4,4′-(oxydi-p-phenylene)dibutanoic acid (XaaX) and 2-methoxyisophthalic acid (XbbX), with a nonsymmetric monomer (YcdY), 4-aminobenzhydrazide, using the condensing agent diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonate ( 1 ). The polymerization was carried out by a one-pot procedure, that is, mixing the dicarboxylic acids, condensing agent 1 and triethylamine in NMP for 2 h at room temperature, followed by the addition of 4-aminobenzhydrazide. This polymerization proceeded smoothly, yielding the ordered polymer with an inherent viscosity of 0.34 dL g⁻¹. The microstructure of the ordered polymer was confirmed by comparing the authentic ordered polymer in their ¹³C-NMR spectrum. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2309–2314, 1998     

Reaction of dichlorocarbene with 1-(2,4,6-tri-t-butylphenyl)-1-phosphaallenes

1-(2,4,6-Tri-t-butylphenyl)-1-phosphaallene reacted with dichlorocarbene to give 2-dichloromethylene-1-(2,4,6-tri-t-butylphenyl)-1-phosphirane. The structure was confirmed by X-ray crystal structure analysis. A similar isomerization product was obtained in the reaction of dichlorocarbene with 3-phenyl-1-(2,4,6-tri-t-butylphenyl)-1-phosphaallene.     

New bitter-tasting hemiterpene glycosides from the Japanese fern Hymenophyllum barbatum.

Hymenosides G--J were newly isolated from the Japanese fern Hymenophyllum barbatum, in addition to hymenosides A--F. The structures of hymenosides were elucidated by extensive two-dimensional nuclear magnetic resonance and/or chemical evidence. The structures of those aglycones were divided into three types, 1,4-dihydroxy-2-hydroxymethyl-but-2-ene, 1,4-dihydroxy-2-methyl-but-2-ene, and 3-hydroxy-5-hexanolide. The sugar moieties were also established by chemical and spectroscopic methods, which were acylated by phenylacetic acid derivatives. These glycosides had a bitter or weakly pungent taste.     

Unique Insertion Mode of 1,7‐Octadiene in Copolymerization with Ethylene by a Constrained‐Geometry Catalyst

Summary: The copolymerization of ethylene and 1,7‐octadiene (OD) was investigated with a constrained‐geometry catalyst. The ¹³C NMR spectrum of the copolymer indicated cyclization insertion of the OD unit in the penultimate position after a single ethylene insertion step. This unique insertion mode of OD forms a 1,5‐disubstituted cyclononane unit in the main chain of polyethylene.

Copolymerization of ethylene and 1,7‐octadiene (OD) with a constrained‐geometry catalyst.     

Effect of accelerating voltage on crystallization of self-standing W-nanodendrites fabricated on SiO2 substrate with electron-beam-induced deposition

Self-standing W-nanodendrite structures were grown on SiO₂ substrate using an electron-beam-induced deposition (EBID) process with various accelerating voltages from 400 to 1000 kV. Effect of accelerating voltage on crystallization of the nanodendrites was investigated. The nanodendrites consisted of nano-sized grains and amorphous structures. The nano-sized grains were determined to be W crystal in BCC structure. The higher was electron beam accelerating voltage, the higher was crystallinity of the as-fabricated nanodendrites. It is suggested that high-energy electron irradiation enhances diffusion of W atoms in the nanodendrites, promotes crystallization of W grains.     

Superconductivity and pseudogap states studied by microwave conductivity measurements of λ-(BEDT-TSF)2GaCl4

We have investigated the microwave response at 45 GHz in an organic superconductor λ-(BEDT-TSF)₂GaCl₄ with T_c = 4.8 K. We determine the μ₀H_c2–T phase diagram from microwave loss and find that the superconducting state is in the pure limit (l/ξ_GL  10). Although the real part of the complex conductivity (=σ₁ + iσ₂) does not show a coherence peak just below T_c, the London penetration depth completely saturates at low temperatures down to T/T_c = 0.2, which may provide an evidence for a conventional s-wave pairing. In the metallic state below about 50 K, (parallel to the c-axis) deviates downward from , while σ₂, which should be zero in a conventional metal, increases exponentially toward T_c. In spite of the fact that the Hagen–Rubens limit is well satisfied as far as the dc conductivity is concerned, a Drude model is unable to explain the large positive σ₂. In order to explain such anomalies in the metallic state, we propose a possible existence of so-called a pseudogap near a Fermi level. The anomalous increase of the positive σ₂ may be attributed to an appearance of pre-formed electron pairs in the pseudogap state. This appearance can be regarded as a precursor to the superconducting transition. Such a precursory phenomenon has been observed also in the isostructural FeCl₄ salt with the anomalous metallic states, which shows a negative σ₂ in contrast to the GaCl₄ salt. Just the opposite of ground states in between the GaCl₄ and FeCl₄ salts may result in the contrasting anomalous metallic states with different precursory phenomena with opposite signs of σ₂.     

Photoisomerization of benzylidenephosphine containing phosphorus in low coordination state

$\text{E}$-Benzylidene-$\text{P}$-2,4,6-tri-$\text{t}$-butylphenylphosphine containing phosphorus in low coordination state was irradiated to give the corresponding $\text{Z}$-isomer: both isomers were isolated and characterized and the reactions with chromium(O) carbonyls were described.