Ryoichi Nishida

Growth of amorphous carbon nanotube from poly(tetrafluoroethylene) and ferrous chloride

Abstract The formation process of an amorphous carbon nanotube (α-CNT) from poly-(tetrafluoroethylene) using ferrous chloride was investigated by observing the TEM images of the isolated intermediates and conducting in situ TEM observation of its formation. These observations revealed unique features of the nanotube growth process through a series of steps; the growth of the core whisker, the deposition of amorphous carbon fragments onto the core whisker, and the disappearance of the core whisker, leaving the α-CNT. Such a unique process suggests a new method of controlling the carbon nano structure through the deposition of carbon over the core whisker template. The stable fluoride form of the core whisker is a key to preparing the amorphous carbon wall on its surface.

Electroreductive synthesis of oligosilanes and polysilanes with ordered sequences

Abstract The stepwise elongation of SiSi or SiGe chain was achieved by the electroreductive cross-coupling reaction of chlorohydrosilanes with dichlorooligosilanes using magnesium electrodes. The electroreductive cross-coupling reaction of chlorodimethylsilane ( 1 ) with dichlorodiphenylsilane ( 2 ) or dichlorodiphenylgermane ( 4 ), for instance, gave 1,3-dihydro-1,1,3,3-tetramethyl-2,2-diphenyltrisilane ( 3 ) or bis(hydrodimethylsilyl)germane ( 5 ) in good yield. Compounds 3 and 5 were readily transformed to the corresponding 1,3-dichlorotrisilane ( 6 ) and bis(chlorosilyl)germane ( 7 ), respectively. The electroreductive polymerization of the resulting dichlorooligosilanes using magnesium electrodes in tetrahydrofuran was successfully applied to the synthesis of sequence-ordered polysilanes.

Electroreductive formation of polysilanes

Electroreduction of dichlorosilanes, such as 1,1-dichlorodialkylsilanes, 1,2-dichlorotetra-alkyldisilanes, and 1,4-bis(chlorodialkylsilyl)benzenes, with Mg electrodes in a single-compartment cell was found to yield the corresponding polysilanes.

Supercritical Hydrogen Adsorptivity of Amorphous Carbon Mesotubes

High-pressure adsorption isotherms of hydrogen onto amorphous carbon mesotubes (ACMs) prepared from fluorine polymer and onto activated carbon fibres (ACFs) were measured at temperatures of 77, 196 and 303 K, respectively, at pressures up to 10 MPa. The adsorption isotherms for ACMs and ACFs at 77 K exhibited maxima at 1 MPa (8.0 wt%) and 4 MPa (3.7 wt%), respectively, although both isotherms at 303 K were of the Henry type and both amounts of hydrogen adsorbed at 8 MPa were less than 0.3 wt%. The maximum hydrogen adsorption amount for ACMs per unit micropore volume as determined by N2 adsorption was 10-times larger than that for ACFs. ACMs are different from ACFs in that they are thought to have specific ultramicropores, although characterization using high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy showed that they possessed a nanographitic structure similar to that of ACFs.

Preparation and optical properties of doubly-oriented poly-(di-methyl-silane) films

Doubly-oriented films of poly-(di-methyl-silane) (PDMS) were prepared by evaporation under controlled conditions on unidirectionally oriented poly(tetra-fluoro-ethylene) (PTFE) thin layer, which was mechanically deposited on fused quartz plate. It was confirmed by X-ray diffraction and polarized absorption measurements that the silicon backbone chains with all-trans conformation laid along the direction of PTFE orientation, and that a particular crystalline plane (110) was parallel to the PTFE layer. PDMS films with double orientation showed a new absorption which appeared only in the polarized spectrum parallel to the direction of chains, and in lower energy region, than the main peak at 4.1 eV.